Final Report Summary - ECONAM (Electromagnetic characterization of nanostructured materials)
Executive summary:
Nanostructured electromagnetic materials are rapidly maturing and become increasingly employed for design of the electronic and optical components, integrated circuits and functional devices. For such applications, the electromagnetic parameters of materials are of the primary importance. However, the measurements and extraction of the electric parameters of nanostructured materials poses enormous conceptual challenges, especially for new materials with exotic electromagnetic properties. At this stage, neither the commonly-accepted test procedures nor a unified set of electromagnetic parameters have been defined and adopted for certification of nanostructured electromagnetic materials in different frequency ranges (microwave, THz, optical).
The main project objective was to consolidate efforts and bring coordination in the European work towards the development, testing, and dissemination of methods and tools for electromagnetic characterisation and metrology of nanostructured composite materials. The respective characterisation techniques should be developed, tested, compared, catalogued and disseminated to the standardisation bodies, industries and Small and medium-sized enterprise (SME)s. The project was aimed at initiating and coordinating cohesive actions in all the aforementioned directions.
The main theoretical results of the project work (analysis of the current status and recommendations for characterisation procedures and for future research) have been structured as a series of documents available at the project web site and disseminated via conferences (including special sessions organised by the consortium) and overview publications. Furthermore, the results have been collated in the coherent tutorial-level text, prefaced by a non-specialist level introduction into the electromagnetic properties of nanostructured materials and their effective parameters.
The content of the project web site (http://econam.metamorphose-vi.org) is one of the main achievements, as it accumulates and presents all the project results to all target audiences, rising their awareness on the critical points in the area. The site has sectioning 'for beginners', 'for specialists', and 'for industrialists', and plethora of materials, especially of tutorial and introductory nature. The new web site layout helps the users with various backgrounds to find the materials which are directly targeted to them. In addition, the project web site has a separate menu which provides a step-by-step guide to the user, bringing the relevant materials in the logical and easy-to-use way. Educational activities of the Coordinated support action (CSA) were organised in form of tutorial lectures and in form of short (up to one week) focused doctoral schools. Especially the school organised during the last year of the project was a success, since that was a unique event where the students had a chance to actually make characterisation measurements as well as interpret their results.
Overall, analysing the most recent literature and conference presentations in the field of electromagnetic characterisation of complex materials, we can conclude that the project has reached its main objective to 'consolidate efforts and bring coordination in the European work towards development, testing, and dissemination of methods and tools for electromagnetic characterisation and metrology of nanostructured composite materials' and has certainly made impact to:
1. capacity building in Europe in nanometrology;
2. improved reliability of measurement and analysis at the nano-level;
3. support to research and regulation, as was stipulated by the NMP call on CSA on material characterisation.
The project work has been praised by a number of users (SMEs and FP7 NMP projects, in particular) via the feedback posted on the project web site.
Project context and objectives:
Nanostructured electromagnetic materials are rapidly maturing and become increasingly employed for design of the electronic and optical components, integrated circuits and functional devices. A broad class of applications is based upon the specialised electromagnetic materials that provide the necessary functionality for electronic devices and constitute the physical layer of the technologies dealing with electromagnetic signals. For such applications, the material electromagnetic parameters (permittivity, permeability, chirality parameter, grid impedance) are of the primary significance. Characterisation and metrology of the engineered nanostructured electromagnetic media have become the critical aspects of their development and utilisation in practical applications. The main novel characterisation approaches are focused on intrinsically interrelated developments and harmonisation of the material phenomenological models, standardisation of characteristic parameters and measurement techniques for evaluating the specified parameters. Usually the basic properties of conventional dielectrics and magnetic materials are described by permittivity and permeability. There are no means for the direct measurement of the electromagnetic parameters, which are dependent on the model used for their extraction. The approaches to measurements of even these fundamental electromagnetic characteristics of materials vary dramatically for electromagnetic waves of different frequencies, e.g. radio waves and light, and require specialised measurement techniques. These difficulties are dramatically escalated in electromagnetic characterisation and metrology of nanostructured materials. At the present stage of research, development and exploitation of nanoparticles and nanocomposites, they are characterised only in terms of geometrical parameters (particle size, lattice period) and sometimes by chemical reactivity. Electromagnetic characterisation of nanocomposite materials and understanding the structure electromagnetic properties relationship, especially in the optical range, is a novel field of electromagnetic science. A comprehensive phenomenological description, with definitions and a consistent metrology of the constitutive electromagnetic parameters of nanocomposites are paramount for their applications. Examples of nanocomposites include photonic crystals and optical metamaterials (arrays of plasmonic nanowires, carbon nanotubes, artificial optical magnetics, super and hyper-lenses). The present lack of established, adequately tested, and widely adopted characterisation methods, tools and test procedures suitable for unambiguous description of electromagnetic properties of nanocomposites hinders further development and use of novel materials in practical applications, especially in optical devices and sensors.
The main challenges in electromagnetic characterisation and metrology of nanostructured materials include the mesoscopic scale and regime of operation. In the majority of practically realisable nanostructures the nanoparticle feature sizes and the characteristic lattice constants are smaller than the operational wavelength of light but comparable with it. For example, a device can operate at the wavelength of 500-600 nm, the structural periodicity is 50-100 nm, and the particle sizes are of the order of 30-70 nm. Such structures can still be described in terms of effective parameters (permittivity and permeability) of an equivalent homogeneous medium. However, the conventional models based on quasi-static homogenisation procedures normally applied at the atomic level are not applicable here, and the resulting effective phenomenological parameters (like permittivity and permeability) have different physical meaning as compared with conventional materials.
The following picture illustrates some typical geometries of nanostructures which have been of main interest of this CSA (pictures taken from journal publications).
The main problems which were addressed by the CSA project:
- The complex geometry and plasmonic resonances of individual nano-inclusions, which form a composite material, cause material resonances even for electrically dense composites. The standard description using the models of a homogenised effective medium is inapplicable near these resonant frequencies.
- Realisable nanocomposite films usually contain only a few layers of nanoparticles (often just one layer). The description of layer properties in terms of bulk material parameters (permittivity and permeability) has limited validity.
- The lack of consistent phenomenological models and established system of the characteristic parameters of nanostructured materials inhibit the development of coherent measurement methodologies and material metrology.
In the present situation, when approaches to electromagnetic characterisation of nanocomposites are only at the incipient stage, researchers either avoid the use of the conventional material parameters for such structures or extend the existing standard definitions beyond the limit of their applicability thereby sometimes violating the basic physical principles of causality, passivity and other fundamental laws. Due to the very nature of the nanostructured materials, the effective electromagnetic parameters have limited application range, but these constraints are yet not well defined and even the existing knowledge is not properly disseminated. As a result, the material users in industries and SMEs often cannot adequately exploit the measured parameters of nanostructures for design of new devices. It is obvious that in this situation, considerable coordination efforts are needed for timely solution of the current problems in electromagnetic characterisation of nanomaterials, and that was the main goal of this CSA.
The main project objective was to consolidate efforts and bring coordination in the European work towards development, testing, and dissemination of methods and tools for electromagnetic characterisation and metrology of nanostructured composite materials. The necessary characterisation techniques should be developed, tested, compared, catalogued, as well as disseminated to the standardisation bodies, industries and SMEs. The project was aimed at initiating and coordinating cohesive actions in all the aforementioned directions.
The main expected impact is in the development and dissemination of novel techniques for electromagnetic characterisation of nanostructured materials. This will complement the known techniques for characterisation in terms of particle and reactivity by developing unified approaches to characterisation in terms of permittivity, permeability, chirality parameter, surface impedance, grid impedance and similar relevant parameters.
Project results:
A description of the main CSA results
In order to achieve the project goals, this coordination support action organised the following main activities.
A representative group of the leading scientists working in this area of research and development was convened and became the core partners of this CSA. They established expert consultative groups. Because the project funding could be used only to support the work of the project partners, the active core of the expert consultative groups was formed by the project beneficiaries. However, the project was able to attract a volunteer representative of the National Physical Laboratory (UK) as a member of one of the groups. The group members were responsible for organisation of all the activities as well as dissemination and reporting. Active participation of a wide scientific and technical community was ensured by active discussions during the special conference sessions organised by CSA at the relevant major international conferences and by wide dissemination and educational activities of the CSA.
The expert consultative groups:
- shared their own knowledge in this area, searched and gathered information from all available sources;
- systemised the information, discussed and evaluated the current trends and achievements in this field;
- established a forum and coordinated efforts in the development and harmonisation of the methodologies for modelling, characterisation and parameter specifications of nanostructured materials;
- coordinated activities in the development of the measurement methodologies and test procedures;
- prepared materials for dissemination and knowledge transfer.
The work of expert groups and dissemination activities were supported by the dedicated web pages of the project and also by the dedicated web facilities available at the METAMORPHOSE virtual institute web portal (http://www.metamorphose-vi.org/). New tools such as a specialised database on characterisation facilities were created. Web-based video lectures and courses for dissemination of knowledge were created and made publicly available at the project web site.
One of the main project dissemination activities resulted in the brochure 'Nanostructured Metamaterials'. It is available for downloading from the European Union (EU) EC website for free (http://ec.europa.eu/research/industrial_technologies/pdf/brochure-metamaterials_en.pdf) or can be ordered from the EU bookshop website.
Special attention was paid to the educational activities for students, Doctor of Philosophy (PhD) students, researchers and engineers, especially from SMEs. This was done mainly by means of international doctoral-level schools on the subject of the CSA and via educational materials targeted to specific audiences and available at the project web site.
The project were made available in form of web resources of various types and posted to the project web site as soon as they were ready. Each deliverable was posted on the web site as a separate file but also as a part of the cohesive tutorial arranged as a set of interrelated web pages with a guiding menu. This way the web site was built as a dynamically growing and re-structuring tool, under development from the start to the end of the active project life.
The CSA activities were organised in Work package (WP)s, and in the following we present the main results and achievements for each CSA WP.
WP1 - Expert consultative group on the theory and modelling of electromagnetic characterisation of nanostructured materials
(WP leader Prof. C.R. Simovski, Aalto University, Finland)
The objective of this WP was to collect, digest and disseminate the state-of-the-art information and identify future research directions in the theoretical and modelling aspects of the electromagnetic characterisation of nanostructured composite materials in the optical frequency range using analytical and numerical methods.
The work was coordinated and lead by the members of the expert consultative group (participants of the CSA consortium), but the results should be credited to the wide scientific community owing to their active participation in discussions at the conference special sessions organised by ECONAM CSA and via informal exchanges with the ECONAM partners.
The following picture illustrates the electromagnetic characterisation roadmap which goes from measurement of electromagnetic response of the sample (such as reflection coefficient) via some material parameter extraction procedure to the physical interpretation of the obtained results.
The main problem which the CSA addressed is that in the majority of situations for complex nanostructures, the conventional methods of retrieval of the characteristic parameters (like the permittivity and permeability) lead to non-physical and, thus, practically useless results. At the first stage of the project, this expert group made an analysis of the scientific and technical literature and found that indeed there is a severe lack of applicable characterisation techniques for nanostructures and for nanostructured metamaterials in particular. The detailed literature overviews with expert analysis of advantages and drawbacks of different methods were produced and the stringent restrictions of the known methods were explained.
Next, the project produced surveys of the most common mistakes and pitfalls in the electromagnetic characterisation of nanostructured composite materials when the conventional and known methods are used.
The next step was the consolidation of the collected information towards creating physically sound and practically applicable characterisation methods and identifying the applicability limits for the classical methods. To this end, the project developed a classification of nanostructured materials including metamaterials and general approaches to their electromagnetic characterisation. The most promising (physically meaningful and practical) methods which are currently under development were identified and this knowledge was disseminated and promoted in order to encourage their development and use.
The aforementioned activities were targeted towards experts in the electromagnetic properties of complex materials and especially in electromagnetic characterisation. In addition, a range of activities was organised in order to reach the wider scientific and technical community, especially experts in nanofabrication. Links between electromagnetic, structural and chemical characterisations were explained in a dedicated deliverable. An educational brochure 'Nanostructured Metamaterials' contains chapters on the theoretical aspects of electromagnetic characterisation as well as an overview introduction to the electromagnetic properties of materials in general. These chapters are accessible to a broad community of material scientists and experts in nanofabrication as well as to non-specialists in this field.
Furthermore, educational and overview lectures were developed and presented to participants of new NMP projects on fabrication on metamaterial structures in a special workshop organised by ECONAM in Brussels.
The WP work results are summarised in the consolidated public overview available in form of a separate document (deliverable D1.1.6) and as a part of a tutorial overview of approaches to electromagnetic characterisation of nanostructured materials (both are available at the project website). The final review and recommendation documents contain a discussion of the suggested road map for future research and development.
The WP results were disseminated via the project web site, presentations and discussions at scientific conferences as well as via review presentations and publication of review papers (see more details in the dissemination section of this report).
WP2 - Consultation and support of the research community and third parties on the measurement techniques and standards in measurements
(WP leader: Prof. Alex Schuchinsky, Queens University of Belfast, UK)
The work of this WP was organised and lead by the expert consultative group on measurement techniques. The group has the following tasks:
- Prepare detailed overviews of the state-of-the-art and most promising measurement techniques employed for retrieval of the phenomenological electromagnetic parameters of nanostructured materials, make analysis and identify future research directions.
- Develop recommendations for electromagnetic researchers and material scientists for choosing the best measurement technique for electromagnetic characterisation consistent with the definitions of the phenomenological electromagnetic parameters. Produce, gather and systemise information for regular updates of the website content for SMEs and industries.
- Provide suggestions on how to characterise electromagnetic properties of the materials under development in the manufacturing projects (FP7 NMP).
This has been a challenging set of tasks. Indeed, optical metamaterials, because of their typically limited area and number of functional layers, are more easily understood as finite structures with interfaces that define their optical behaviour. This definition is in contrast to a conventional material in which their bulk properties define their optical properties. The retrieved 'material' parameters are a subject of interpretation unless the samples have sufficient extent in the direction of wave propagation to neglect the interface effects. Also the phase information is more difficult to obtain. It requires either more sophisticated measuring tools, such as time domain or interference methods, or alternatively, more complex structures, e.g. phase masks made with the metamaterial. As a result, there is no simple and universally applicable measurement technique and test equipment. Moreover, the method for extraction of effective electromagnetic parameters from measured results should be carefully chosen for every particular sample, and the results must be thoroughly examined for their consistency with the fundamental physical principles.
In the first task, the detailed overview of the available experimental techniques has been developed step-by-step. During the first project year, the first version was created, which was then broadly discussed at the special conference sessions organised by the project as well as via individual discussions with experts in the field (including non-European experts). This material contributed in part to the popular brochure 'Nanostuctured Metamaterials', published by the European Commission. The overview document was updated every six months, and finally, a consolidated overview of the state-of-the-art and most promising measurement techniques employed for retrieval of the phenomenological electromagnetic parameters of nanostructured materials has been compiled at the end of the project. This final document has been disseminated via the project web site as a separate document, as a part of the logically structured tutorial, and finally it contributed to the extensive tutorial overview of the approaches to electromagnetic characterisation of nanostructured materials, which is one of the major project outputs.
Similarly to the work done by the expert group of WP1, the results should be credited not only to the members of the expert group, but also to a broad scientific community actively participated in discussions at the conference special sessions organised by ECONAM CSA and via informal research exchange with the ECONAM partners.
Work on the second task was mainly targeted at the development and structuring of the informative and tutorial materials for the project website. The result is a web site where scientists and engineers (both experts in electromagnetic characterisation of materials and users of measurement equipment), as well as industrialists can find credible information and recommendations presented in a structured and targeted form. The web tools include informative databases of appropriate equipment as well as information about availability of the necessary equipment in European institutions, as well as technical recommendations and scientific explanations of parameter extraction procedures.
Work on the last task (provide suggestions on how to characterise electromagnetic properties of the materials under development in the manufacturing projects (FP7 NMP)) resulted in the development of a roadmap for experimental characterisation of metamaterials. This tool (available on the project website) provides a step-by-step guidance on how to determine experimentally what kind of structure is tested and, if this is indeed a new material, how to assess the electromagnetic properties of composite material samples. The following picture illustrates the layout of the road map (only the first step is shown). This roadmap has two versions - one is for non-specialists and the other for experts in the field. In the latter version, additional details are given as well as recommendations are provided for future work on the development of experimental techniques. The road map has accumulated the results of the work performed in this project and, according to the schedule, was finalised at the end of the project. These results have been posted on the project web site and will be promoted by the project participants beyond the project lifetime. Naturally, adoption of the novel advanced characterisation techniques will require extensive discussions in the wide scientific community and it will involve a number of iterations before becoming universally accepted.
WP3 - Access to measurement facilities, computational tools and data banks
(WP leader Dr Vladimir Podlosny, Metamorphose Virtual Institute, Belgium)
This WP organised access for SME and other interested organisations in Europe to the existing measurement, computational and data resources at the public laboratories of the project beneficiaries. Also it facilitated access to other European EM NSM characterisation centres via information management activities and promotional actions. The organised access (not only to the facilities of the project beneficiaries but also to other leading European organisations) was provided via a number of tools developed and posted on the project web site. The WP has collected information about the available facilities and made it accessible in form of well organised and searchable databases published on the web site.
The following laboratories contributed to the facilities database:
- Institut fur Photonik und Quantenelektronik, Karlsruhe University, Karlsruhe, Germany.
- Laboratory of Physical Chemistry, Swiss Federal Institute of Technology Surich, Switserland.
- Institute for Atomic and Molecular Physics, Amsterdam, Netherlands.
- Nanophotonic, Institut of Physics, Faculty of Mathematics and Science, Technical University of Ilmenau, Ilmenau, Germany.
- Nanobiotechnology-Group, Gutenberg Universität, Mains, Germany.
- Physikalisches Institut, Physiksentrum, RWTH, Aachen, Germany.
- Physikalisches Institut, Universitaet Stuttgart, Stuttgart, Germany.
- Centre for Innovation Competence, Institute of Applied Physics, Friedrich Schiller University Jena, Jena, Germany.
- The Institute for Nanotechnology, University of Karlsruhe, Karlsruhe, Deutschland.
- Optoelectronics Research Centre, University of Southampton, Southampton, UK.
- Centre for Solid State Physics and New Materials, Belgrade, Serbia.
- Centre for Surface and Nanoanalytics, Lins, Austria.
- Sentech Instruments GmbH, Berlin, Germany.
- Institute of Applied Physics Friedrich-Schiller-Universität Jena, Jena, Germany.
- Institute for Analytical Sciences, Berlin, Germany.
The laboratory profiles contain also information about access rules currently adopted at each site.
The appropriate facility or computational tool can be found in accordance with the type of measurement or the type of equipment or by the type of material under study. Each facility is described in detail, including the contact information of the local person responsible for organisation of access by external users.
The access tools developed by the ECONAM project were promoted through web-posted news, via review presentations at conferences and review papers describing ECONAM project activities.
WP4 - Dissemination, education, and training
(WP leader Prof. Filiberto Bilotti, University Roma Tre, Italy)
Special efforts and measures are needed to deliver new knowledge, new measurement techniques, and approaches to extraction of effective material parameters. The main current problem in the area of research and development that we addressed by this CSA is that there are no well-developed and commonly accepted characterisation techniques. The recent achievements in electrodynamics of nanocomposites have shown that it is impossible to apply the existing concepts of electromagnetic characterisation of materials to nanocomposites. In the situation when this new knowledge is not properly disseminated, it may lead to negative unpredictable consequences. For example, the old concepts are used as the theoretical foundation of software used in the commercial measuring devices (ellipsometers). This means that in majority of situations the measured parameters cannot be utilised in device design because the physical meaning of the parameters is not clear or even wrongly defined. It is obvious that there is a pressing need to disseminate the latest knowledge in this field and promote creation of commonly accepted characterisation techniques. Furthermore, the users of new nanostructured materials should be educated in the area of electromagnetic characterisation, so that they can use the measured parameters to predict material performance in a particular device.
The dissemination activities are targeted towards: (a) researchers in electromagnetic and material science, (b) industries and SMEs, as well as (c) general public. Next we present the WP results in each of its tasks.
The first task was to organise European School Events on NSM characterisation of advanced electromagnetic materials each year. This work was led by the Metamorphose Virtual Institute and completed successfully. School on 'Fabrication and optical properties of nanostructured metamaterials' was organised in conjunction with the '8th International conference on electrical transport and optical properties of inhomogeneous media' (ETOPIM8) on Crete, Greece, 12-13 June 2009. The illustration shows the home page of that school event.
The ECONAM project contributed to the one-week international school on Fundamentals of Metamaterials Electromagnetics (16-20 November 2009, Levi, Finland), with three (out of four) lecturers provided by the ECONAM project partners.
In the last year of the ECONAM project activities, the project organised a week-long school on experimental electromagnetic characterisation of complex materials and metamaterials. Below is a picture showing the home web page of this event.
All the school events have got most positive feedback from the participants.
The second task was to prepare online and offline web-based electronic courses on NSM characterisation. This work resulted in an extensive video tutorial lecture available for download from the project web site, as well as in an educational section on the web site. In addition, all the lectures presented at the doctoral school events have been recorded as video files or as a set of slides and all these materials have been posted on the doctoral school web site.
The next task was to organise special sessions on electromagnetic characterisation techniques and existing European facilities for NSM at the METAMATERIALS Congress and other conferences.
The main efforts of this CSA were on coordination and support to the European work towards development, testing, and dissemination of methods and tools for electromagnetic characterisation and metrology of nanostructured composite materials (metamaterials). Based on this, for discussions of problems of electromagnetic characterisation of composite materials we have chosen the main forums where experts in this area of nanoscience and material science meet: Metamaterials 2008 (Pamplona) and 2009 (London), Meta'2010 (Cairo), and others. The dissemination efforts were directed to a wider audience including other areas of nanoscience and material science, as well as potential applications of novel electromagnetic properties of nanostructured metamaterials. These conferences include Material research society (MRS) meeting, forum on new materials, electromagnetics in advance applications, and others.
Below we provide some details about the most prominent events.
Metamaterials congress (http://congress2011.metamorphose-vi.org/) organised by the Metamorphose virtual institute (one of the beneficiaries of the ECONAM project) has been one of the main dissemination engines for ECONAM.
A panel session organised by the ECONAM project has been convened at the second congress on 'Artificial electromagnetic materials for microwaves and optics', Metamaterials 2008 held in Pamplona, Spain on 21-26 September 2008. The session entitled 'Theoretical issues and practical aspects of metamaterial characterisation' has been organised by Prof. A. Schuchinsky (partner of ECONAM) and Prof. R. Mittra, Pennsylvania State University, USA. The panellists were the following:
- Prof. Sergei Tretyakov, Helsinki University of Technology, Finland (ECONAM partner).
- Prof. Allan Boardman, University of Salford, UK.
- Prof. Ricardo Marques, University of Seville, Spain.
- Prof. Stefan Linden, Karlsruhe University, Germany (ECONAM partner).
- Prof. Yang Hao, Queen Mary University of London, UK.
- Prof. Raj Mittra, Pennsylvania State University, USA.
- Prof. Alex Schuchinsky, Queen's University Belfast, UK (ECONAM partner).
The panel session attended by more than 100 participants of the congress comprised brief presentations by the panellist followed by the extensive interactive discussion involved both the panellists and audience. The session materials are available at the ECONAM website. A special session entitled 'Progress of the ECONAM project' was organised at the third international congress on 'Advanced electromagnetic materials in microwaves and optics' - Metamaterials 2009, held in London, UK on 30 August - 4 September 2009. In the ECONAM special session there was massive participation of NMP audience, especially of experts in the particular field of this CSA (electromagnetic characterisations of nanostructured materials).
Here is the list of presented papers: Henrik Wallén, Henrik Kettunen, Ari Sihvola, Helsinki University of Technology (AALTO), Finland, Applicability of classical mixing rules: from positive to negative parameters Costas Soukoulis, J. Shou, M. Kafesaki, Th. Koschny, Foundation for Research and Technology Hellas (FORTH), Greece, Weakly and strongly coupled optical metamaterials Chris Fiets, Dmitriy Korobkin, Burton Neuner, Department of Physics, Chihui Wu, Gennady Shvets, Department of Physics, The University of Texas at Austin, USA, Characterisation of plasmonic metamaterials using effective parameters Constantin Simovski, Helsinki University of Technology (AALTO), Finland, On the locality of Drude transition layers for metamaterials Alexey Vinogradov, Alexander Merslikin, ITAE, Russia; Said Souhdi, Laboratoire de Génie Electrique de Paris LGEP-Supélec, France, On non-Maxwellian boundary conditions for metamaterial interface.
As is seen from this list, participation of experts from outside the ECONAM participants was ensured, and it was the key for the meeting success.
In 2010, ECONAM organised a special ECONAM session at conference META 2010 (Cairo). This event was very well attended by experts in nanoscience and material science, working on electromagnetic properties of nanostructured materials. At this session, intermediate results of WPs 1,2 have been disseminated, and, most important, the members of ECONAM expert consultative groups met each other and other distinguished experts in the fields, which resulted in decisive contributions to the analysis and recommendations presented in updates to a number of deliverables.
The session was introduced by a keynote presentation by A. Vinogradov (ECONAM partner ITAE) entitled 'Homogenisation of metamaterials: bulk properties and boundary conditions'. In this talk the pitfalls of different approaches of introduction of effective constitutive parameters were considered. Today we encounter a situation that remembers one in the beginning of the twenty century. It was the time of a crisis of classical mechanics, which finished with creation of relativistic theory and quantum mechanics. Now we go through the crisis of classical electrodynamics of condensed matter developed by Maxwell, Heaviside and Lorentz. Indeed, as in the beginning of twenty century, we observe an increase of experimental results that can hardly be explained with the existent theories.
Here is the list of the other papers presented at the session:
- Yu. E. Lozovik (ITAE), Electromagnetic characterisation of graphene and graphene based nanostructures.
- A. G. Schuchinsky (QUB), A. Vallecchi, A.P. Shitvov and F. Capolino, Resonance transmittance in metamaterials made of stacked arrays of dogbone shaped conductor pairs.
- S. Larouche and D. R. Smith, Quantifying the nonlinear susceptibility of metamaterials.
- D. Mogilevtsev, F. A. Pinheiro, R. R. dos Santos, S. B. Cavalcanti and L. E. Oliveira, Anderson localisation in disordered dispersive metamaterials.
- M. H. Belyamoun, A. Bossavit and S. Souhdi, Frequency-dependent homogenisation of split-ring arrays.
- R. Kotynski, T. Stefaniuk, A. Pastusscsak, Sub-wavelength diffraction-free imaging in low-loss metal-dielectric multilayers.
The special sessions organised by ECONAM provided an important and timely review of the state-of-the-art in characterisation of artificial electromagnetic materials, which was later recorded in updates to ECONAM deliverables and on its web site tools. The papers have been presented by the experts in the field, who addressed the current issues on the definition and determination of the physical parameters suitable for the meaningful description of the metamaterial properties. The sessions represented also an important place where the latest results on the characterisation of nanostructured materials have been discussed and where the experts in the field got together and compared the different approaches used.
Actually this activity was not only a part of work on dissemination - these special sessions were of key importance for the work of the expert consultative groups (WPs 1,2). At these sessions the preliminary results of the expert group work were discussed within the wide international scientific community, and here the experts of the project collected information on the latest developments in the field of their expertise, which was then used to update and develop the analytical reviews and recommendation documents of the ECONAM project. As explained above, due to the Seventh Framework Programme (FP7) financial rules it was not possible to involve more external experts into the project consultative groups directly, and these special sessions were successfully used as a tool to dramatically widen the scope of the project activities due to participation of experts not directly involved in the ECONAM project.
The task on writing the monograph on electromagnetic characterisation of nanostructured materials has resulted in the tutorial overview of approaches to electromagnetic characterisation of nanostructured materials. This extensive document (79 pages) has been formed and edited as the combined and structural output of the whole work of the Expert Consultative Groups during the whole project life. In addition, it contains an introductory chapter on basics of electromagnetic properties of materials. The book is accessible for non-specialists in the field, with appropriate references to original publications for the expert reader. Because this cumulative book was finalised (according to the work plan) at the end of the project, at this stage it could be disseminated only via the project web site. However, the ECONAM consortium is considering possible publication of this text as a book.
The last task of this WP was an educational event for the new FP7 NMP projects on manufacturing of metamaterial structures. The event was organised in December 2009 in Brussels, and was well attended by the beneficiaries of the respective NMP projects. The ECONAM project has organised the event and delivered a set of tutorial lectures not only on the topic of the CSA (electromagnetic characterisation of nanostructured materials) but also tutorials on the basics of electromagnetic properties of materials and their description. Below we present the first slides of the three main lectures.
WP5 - Information and communication support for research and dissemination
(WP leader Dr Vladimir Podloshny, Metamorphose Virtual Institute, Belgium)
Starting from the project outset till its very last days the project web site http://econam.metamorphose-vi.org has been continuously evolving and developed as the main education and dissemination tool of the project. The web site structure has been constantly advanced. Each new deliverable or its update has been promptly posted on the web site and integrated in the overall structured and logical informational and educational skeleton. At the later stages, the web site received an additional menus 'for beginners', 'for specialists' and 'for industrialists', with separate introductions and guidance pages targeted for each of these three categories. The menu 'characterisation' leads the reader step-by-step along the learning process, logically introducing the analytical and recommendation documents generated by the project.
The picture below illustrates the site popularity grows during the first project year.
Promotion of the project website took place at several scientific and technical meetings as well as on a number of commercial and public websites. The key persons participating in ECONAM promoted the site via their personal web sites. Links have been made also from participants' departments and laboratories web pages. The web site link was promoted via review presentations about ECONAM activities, both via the abstracts and proceedings publications and during talks. Promotional video was made and on Youtube: http://www.youtube.com/watch?v=RUar3D-2nTc.
The potential impact
The main impact of this CSA is in the development and dissemination of the novel techniques for electromagnetic characterisation of nanostructured materials and preparing the basis for future standards in the field of nanomaterials characterisation in terms of the electromagnetic parameters. This will complement the known techniques for characterisation in terms of particle and reactivity by developing unified approaches to characterisation in terms of permittivity, permeability, chirality parameter, surface impedance, grid impedance and similar descriptions. These parameters will be able to characterise not only bulk materials, but also thin layers and interface behaviour. Acceptance of these new methods for electromagnetic characterisation will have dramatic impact on nanotechnology applications especially in telecommunications, imaging, detection, and sensors.
The expected long-term impact will be adoption of common measurement tools for the electromagnetic characterisation of nanostructured materials. Such unified measurement methods and tools and the parameter retrieval procedures will be very important for the European industry as this will allow them to use the standard characterisation procedures for applications that involve nanostructured materials. This project has brought a new level of cohesiveness to the field of electromagnetic characterisation of nanostructured materials. Coordination of the experimental measurement techniques and metrology standards used for characterisation of nanostructured materials will result in reliable and reproducible material development efforts which are essential for future applications of nanostructured artificial electromagnetic materials. The benefits for industry and particularly SMEs will include access to the unique equipment and expertise that would ordinarily be too expensive in term of time and cost.
The development and broad adoption of the new characterisation techniques is a long process, but even now we can observe that the impact of ECONAM project is quite visible and tangible. In the scientific and technical community there is much more awareness of difficulties and pitfalls in the conventional characterisation techniques when one applies them to novel complex nanostructures. The analysis of the most recent literature shows that more and more papers attempt to fill the gaps of knowledge in this field and propose new advanced characterisation methods, applicable to metamaterials. We are pleased to see the influence of our efforts on these growing international developments.
The ECONAM project web site is now acting as a virtual European facility for electromagnetic characterisation of nanostructured composite materials, which offers comprehensive information on the well-established, tested, and widely disseminated measurement techniques and methodologies for the material parameter retrieval as well as the detailed knowledge on pitfalls, problematic issues, and novel approaches suitable for emerging complex nanostructured materials. The web site also provides a mechanism for sharing measurement facilities and providing quality metrology services for the industries and SMEs.
Potential impact:
The main impact of this CSA is in the development and dissemination of the novel techniques for electromagnetic characterisation of nanostructured materials and preparing the basis for future standards in the field of nanomaterials characterisation in terms of the electromagnetic parameters. This will complement the known techniques for characterisation in terms of particle and reactivity by developing unified approaches to characterisation in terms of permittivity, permeability, chirality parameter, surface impedance, grid impedance and similar descriptions. These parameters will be able to characterise not only bulk materials, but also thin layers and interface behaviour. Acceptance of these new methods for electromagnetic characterisation will have dramatic impact on nanotechnology applications especially in telecommunications, imaging, detection, and sensors.
The expected long-term impact will be adoption of common measurement tools for the electromagnetic characterisation of nanostructured materials. Such unified measurement methods and tools and the parameter retrieval procedures will be very important for the European industry as this will allow them to use the standard characterisation procedures for applications that involve nanostructured materials. This project has brought a new level of cohesiveness to the field of electromagnetic characterisation of nanostructured materials. Coordination of the experimental measurement techniques and metrology standards used for characterisation of nanostructured materials will result in reliable and reproducible material development efforts which are essential for future applications of nanostructured artificial electromagnetic materials. The benefits for industry and particularly SMEs will include access to the unique equipment and expertise that would ordinarily be too expensive in term of time and cost.
The development and broad adoption of the new characterisation techniques is a long process, but even now we can observe that the impact of ECONAM project is quite visible and tangible. In the scientific and technical community there is much more awareness of difficulties and pitfalls in the conventional characterisation techniques when one applies them to novel complex nanostructures. The analysis of the most recent literature shows that more and more papers attempt to fill the gaps of knowledge in this field and propose new advanced characterisation methods, applicable to metamaterials. We are pleased to see the influence of our efforts on these growing international developments.
The ECONAM project website is now acting as a virtual European facility for electromagnetic characterisation of nanostructured composite materials, which offers comprehensive information on the well-established, tested, and widely disseminated measurement techniques and methodologies for the material parameter retrieval as well as the detailed knowledge on pitfalls, problematic issues, and novel approaches suitable for emerging complex nanostructured materials. The web site also provides a mechanism for sharing measurement facilities and providing quality metrology services for the industries and SMEs.
List of websites: http://econam.metamorphose-vi.org/
Nanostructured electromagnetic materials are rapidly maturing and become increasingly employed for design of the electronic and optical components, integrated circuits and functional devices. For such applications, the electromagnetic parameters of materials are of the primary importance. However, the measurements and extraction of the electric parameters of nanostructured materials poses enormous conceptual challenges, especially for new materials with exotic electromagnetic properties. At this stage, neither the commonly-accepted test procedures nor a unified set of electromagnetic parameters have been defined and adopted for certification of nanostructured electromagnetic materials in different frequency ranges (microwave, THz, optical).
The main project objective was to consolidate efforts and bring coordination in the European work towards the development, testing, and dissemination of methods and tools for electromagnetic characterisation and metrology of nanostructured composite materials. The respective characterisation techniques should be developed, tested, compared, catalogued and disseminated to the standardisation bodies, industries and Small and medium-sized enterprise (SME)s. The project was aimed at initiating and coordinating cohesive actions in all the aforementioned directions.
The main theoretical results of the project work (analysis of the current status and recommendations for characterisation procedures and for future research) have been structured as a series of documents available at the project web site and disseminated via conferences (including special sessions organised by the consortium) and overview publications. Furthermore, the results have been collated in the coherent tutorial-level text, prefaced by a non-specialist level introduction into the electromagnetic properties of nanostructured materials and their effective parameters.
The content of the project web site (http://econam.metamorphose-vi.org) is one of the main achievements, as it accumulates and presents all the project results to all target audiences, rising their awareness on the critical points in the area. The site has sectioning 'for beginners', 'for specialists', and 'for industrialists', and plethora of materials, especially of tutorial and introductory nature. The new web site layout helps the users with various backgrounds to find the materials which are directly targeted to them. In addition, the project web site has a separate menu which provides a step-by-step guide to the user, bringing the relevant materials in the logical and easy-to-use way. Educational activities of the Coordinated support action (CSA) were organised in form of tutorial lectures and in form of short (up to one week) focused doctoral schools. Especially the school organised during the last year of the project was a success, since that was a unique event where the students had a chance to actually make characterisation measurements as well as interpret their results.
Overall, analysing the most recent literature and conference presentations in the field of electromagnetic characterisation of complex materials, we can conclude that the project has reached its main objective to 'consolidate efforts and bring coordination in the European work towards development, testing, and dissemination of methods and tools for electromagnetic characterisation and metrology of nanostructured composite materials' and has certainly made impact to:
1. capacity building in Europe in nanometrology;
2. improved reliability of measurement and analysis at the nano-level;
3. support to research and regulation, as was stipulated by the NMP call on CSA on material characterisation.
The project work has been praised by a number of users (SMEs and FP7 NMP projects, in particular) via the feedback posted on the project web site.
Project context and objectives:
Nanostructured electromagnetic materials are rapidly maturing and become increasingly employed for design of the electronic and optical components, integrated circuits and functional devices. A broad class of applications is based upon the specialised electromagnetic materials that provide the necessary functionality for electronic devices and constitute the physical layer of the technologies dealing with electromagnetic signals. For such applications, the material electromagnetic parameters (permittivity, permeability, chirality parameter, grid impedance) are of the primary significance. Characterisation and metrology of the engineered nanostructured electromagnetic media have become the critical aspects of their development and utilisation in practical applications. The main novel characterisation approaches are focused on intrinsically interrelated developments and harmonisation of the material phenomenological models, standardisation of characteristic parameters and measurement techniques for evaluating the specified parameters. Usually the basic properties of conventional dielectrics and magnetic materials are described by permittivity and permeability. There are no means for the direct measurement of the electromagnetic parameters, which are dependent on the model used for their extraction. The approaches to measurements of even these fundamental electromagnetic characteristics of materials vary dramatically for electromagnetic waves of different frequencies, e.g. radio waves and light, and require specialised measurement techniques. These difficulties are dramatically escalated in electromagnetic characterisation and metrology of nanostructured materials. At the present stage of research, development and exploitation of nanoparticles and nanocomposites, they are characterised only in terms of geometrical parameters (particle size, lattice period) and sometimes by chemical reactivity. Electromagnetic characterisation of nanocomposite materials and understanding the structure electromagnetic properties relationship, especially in the optical range, is a novel field of electromagnetic science. A comprehensive phenomenological description, with definitions and a consistent metrology of the constitutive electromagnetic parameters of nanocomposites are paramount for their applications. Examples of nanocomposites include photonic crystals and optical metamaterials (arrays of plasmonic nanowires, carbon nanotubes, artificial optical magnetics, super and hyper-lenses). The present lack of established, adequately tested, and widely adopted characterisation methods, tools and test procedures suitable for unambiguous description of electromagnetic properties of nanocomposites hinders further development and use of novel materials in practical applications, especially in optical devices and sensors.
The main challenges in electromagnetic characterisation and metrology of nanostructured materials include the mesoscopic scale and regime of operation. In the majority of practically realisable nanostructures the nanoparticle feature sizes and the characteristic lattice constants are smaller than the operational wavelength of light but comparable with it. For example, a device can operate at the wavelength of 500-600 nm, the structural periodicity is 50-100 nm, and the particle sizes are of the order of 30-70 nm. Such structures can still be described in terms of effective parameters (permittivity and permeability) of an equivalent homogeneous medium. However, the conventional models based on quasi-static homogenisation procedures normally applied at the atomic level are not applicable here, and the resulting effective phenomenological parameters (like permittivity and permeability) have different physical meaning as compared with conventional materials.
The following picture illustrates some typical geometries of nanostructures which have been of main interest of this CSA (pictures taken from journal publications).
The main problems which were addressed by the CSA project:
- The complex geometry and plasmonic resonances of individual nano-inclusions, which form a composite material, cause material resonances even for electrically dense composites. The standard description using the models of a homogenised effective medium is inapplicable near these resonant frequencies.
- Realisable nanocomposite films usually contain only a few layers of nanoparticles (often just one layer). The description of layer properties in terms of bulk material parameters (permittivity and permeability) has limited validity.
- The lack of consistent phenomenological models and established system of the characteristic parameters of nanostructured materials inhibit the development of coherent measurement methodologies and material metrology.
In the present situation, when approaches to electromagnetic characterisation of nanocomposites are only at the incipient stage, researchers either avoid the use of the conventional material parameters for such structures or extend the existing standard definitions beyond the limit of their applicability thereby sometimes violating the basic physical principles of causality, passivity and other fundamental laws. Due to the very nature of the nanostructured materials, the effective electromagnetic parameters have limited application range, but these constraints are yet not well defined and even the existing knowledge is not properly disseminated. As a result, the material users in industries and SMEs often cannot adequately exploit the measured parameters of nanostructures for design of new devices. It is obvious that in this situation, considerable coordination efforts are needed for timely solution of the current problems in electromagnetic characterisation of nanomaterials, and that was the main goal of this CSA.
The main project objective was to consolidate efforts and bring coordination in the European work towards development, testing, and dissemination of methods and tools for electromagnetic characterisation and metrology of nanostructured composite materials. The necessary characterisation techniques should be developed, tested, compared, catalogued, as well as disseminated to the standardisation bodies, industries and SMEs. The project was aimed at initiating and coordinating cohesive actions in all the aforementioned directions.
The main expected impact is in the development and dissemination of novel techniques for electromagnetic characterisation of nanostructured materials. This will complement the known techniques for characterisation in terms of particle and reactivity by developing unified approaches to characterisation in terms of permittivity, permeability, chirality parameter, surface impedance, grid impedance and similar relevant parameters.
Project results:
A description of the main CSA results
In order to achieve the project goals, this coordination support action organised the following main activities.
A representative group of the leading scientists working in this area of research and development was convened and became the core partners of this CSA. They established expert consultative groups. Because the project funding could be used only to support the work of the project partners, the active core of the expert consultative groups was formed by the project beneficiaries. However, the project was able to attract a volunteer representative of the National Physical Laboratory (UK) as a member of one of the groups. The group members were responsible for organisation of all the activities as well as dissemination and reporting. Active participation of a wide scientific and technical community was ensured by active discussions during the special conference sessions organised by CSA at the relevant major international conferences and by wide dissemination and educational activities of the CSA.
The expert consultative groups:
- shared their own knowledge in this area, searched and gathered information from all available sources;
- systemised the information, discussed and evaluated the current trends and achievements in this field;
- established a forum and coordinated efforts in the development and harmonisation of the methodologies for modelling, characterisation and parameter specifications of nanostructured materials;
- coordinated activities in the development of the measurement methodologies and test procedures;
- prepared materials for dissemination and knowledge transfer.
The work of expert groups and dissemination activities were supported by the dedicated web pages of the project and also by the dedicated web facilities available at the METAMORPHOSE virtual institute web portal (http://www.metamorphose-vi.org/). New tools such as a specialised database on characterisation facilities were created. Web-based video lectures and courses for dissemination of knowledge were created and made publicly available at the project web site.
One of the main project dissemination activities resulted in the brochure 'Nanostructured Metamaterials'. It is available for downloading from the European Union (EU) EC website for free (http://ec.europa.eu/research/industrial_technologies/pdf/brochure-metamaterials_en.pdf) or can be ordered from the EU bookshop website.
Special attention was paid to the educational activities for students, Doctor of Philosophy (PhD) students, researchers and engineers, especially from SMEs. This was done mainly by means of international doctoral-level schools on the subject of the CSA and via educational materials targeted to specific audiences and available at the project web site.
The project were made available in form of web resources of various types and posted to the project web site as soon as they were ready. Each deliverable was posted on the web site as a separate file but also as a part of the cohesive tutorial arranged as a set of interrelated web pages with a guiding menu. This way the web site was built as a dynamically growing and re-structuring tool, under development from the start to the end of the active project life.
The CSA activities were organised in Work package (WP)s, and in the following we present the main results and achievements for each CSA WP.
WP1 - Expert consultative group on the theory and modelling of electromagnetic characterisation of nanostructured materials
(WP leader Prof. C.R. Simovski, Aalto University, Finland)
The objective of this WP was to collect, digest and disseminate the state-of-the-art information and identify future research directions in the theoretical and modelling aspects of the electromagnetic characterisation of nanostructured composite materials in the optical frequency range using analytical and numerical methods.
The work was coordinated and lead by the members of the expert consultative group (participants of the CSA consortium), but the results should be credited to the wide scientific community owing to their active participation in discussions at the conference special sessions organised by ECONAM CSA and via informal exchanges with the ECONAM partners.
The following picture illustrates the electromagnetic characterisation roadmap which goes from measurement of electromagnetic response of the sample (such as reflection coefficient) via some material parameter extraction procedure to the physical interpretation of the obtained results.
The main problem which the CSA addressed is that in the majority of situations for complex nanostructures, the conventional methods of retrieval of the characteristic parameters (like the permittivity and permeability) lead to non-physical and, thus, practically useless results. At the first stage of the project, this expert group made an analysis of the scientific and technical literature and found that indeed there is a severe lack of applicable characterisation techniques for nanostructures and for nanostructured metamaterials in particular. The detailed literature overviews with expert analysis of advantages and drawbacks of different methods were produced and the stringent restrictions of the known methods were explained.
Next, the project produced surveys of the most common mistakes and pitfalls in the electromagnetic characterisation of nanostructured composite materials when the conventional and known methods are used.
The next step was the consolidation of the collected information towards creating physically sound and practically applicable characterisation methods and identifying the applicability limits for the classical methods. To this end, the project developed a classification of nanostructured materials including metamaterials and general approaches to their electromagnetic characterisation. The most promising (physically meaningful and practical) methods which are currently under development were identified and this knowledge was disseminated and promoted in order to encourage their development and use.
The aforementioned activities were targeted towards experts in the electromagnetic properties of complex materials and especially in electromagnetic characterisation. In addition, a range of activities was organised in order to reach the wider scientific and technical community, especially experts in nanofabrication. Links between electromagnetic, structural and chemical characterisations were explained in a dedicated deliverable. An educational brochure 'Nanostructured Metamaterials' contains chapters on the theoretical aspects of electromagnetic characterisation as well as an overview introduction to the electromagnetic properties of materials in general. These chapters are accessible to a broad community of material scientists and experts in nanofabrication as well as to non-specialists in this field.
Furthermore, educational and overview lectures were developed and presented to participants of new NMP projects on fabrication on metamaterial structures in a special workshop organised by ECONAM in Brussels.
The WP work results are summarised in the consolidated public overview available in form of a separate document (deliverable D1.1.6) and as a part of a tutorial overview of approaches to electromagnetic characterisation of nanostructured materials (both are available at the project website). The final review and recommendation documents contain a discussion of the suggested road map for future research and development.
The WP results were disseminated via the project web site, presentations and discussions at scientific conferences as well as via review presentations and publication of review papers (see more details in the dissemination section of this report).
WP2 - Consultation and support of the research community and third parties on the measurement techniques and standards in measurements
(WP leader: Prof. Alex Schuchinsky, Queens University of Belfast, UK)
The work of this WP was organised and lead by the expert consultative group on measurement techniques. The group has the following tasks:
- Prepare detailed overviews of the state-of-the-art and most promising measurement techniques employed for retrieval of the phenomenological electromagnetic parameters of nanostructured materials, make analysis and identify future research directions.
- Develop recommendations for electromagnetic researchers and material scientists for choosing the best measurement technique for electromagnetic characterisation consistent with the definitions of the phenomenological electromagnetic parameters. Produce, gather and systemise information for regular updates of the website content for SMEs and industries.
- Provide suggestions on how to characterise electromagnetic properties of the materials under development in the manufacturing projects (FP7 NMP).
This has been a challenging set of tasks. Indeed, optical metamaterials, because of their typically limited area and number of functional layers, are more easily understood as finite structures with interfaces that define their optical behaviour. This definition is in contrast to a conventional material in which their bulk properties define their optical properties. The retrieved 'material' parameters are a subject of interpretation unless the samples have sufficient extent in the direction of wave propagation to neglect the interface effects. Also the phase information is more difficult to obtain. It requires either more sophisticated measuring tools, such as time domain or interference methods, or alternatively, more complex structures, e.g. phase masks made with the metamaterial. As a result, there is no simple and universally applicable measurement technique and test equipment. Moreover, the method for extraction of effective electromagnetic parameters from measured results should be carefully chosen for every particular sample, and the results must be thoroughly examined for their consistency with the fundamental physical principles.
In the first task, the detailed overview of the available experimental techniques has been developed step-by-step. During the first project year, the first version was created, which was then broadly discussed at the special conference sessions organised by the project as well as via individual discussions with experts in the field (including non-European experts). This material contributed in part to the popular brochure 'Nanostuctured Metamaterials', published by the European Commission. The overview document was updated every six months, and finally, a consolidated overview of the state-of-the-art and most promising measurement techniques employed for retrieval of the phenomenological electromagnetic parameters of nanostructured materials has been compiled at the end of the project. This final document has been disseminated via the project web site as a separate document, as a part of the logically structured tutorial, and finally it contributed to the extensive tutorial overview of the approaches to electromagnetic characterisation of nanostructured materials, which is one of the major project outputs.
Similarly to the work done by the expert group of WP1, the results should be credited not only to the members of the expert group, but also to a broad scientific community actively participated in discussions at the conference special sessions organised by ECONAM CSA and via informal research exchange with the ECONAM partners.
Work on the second task was mainly targeted at the development and structuring of the informative and tutorial materials for the project website. The result is a web site where scientists and engineers (both experts in electromagnetic characterisation of materials and users of measurement equipment), as well as industrialists can find credible information and recommendations presented in a structured and targeted form. The web tools include informative databases of appropriate equipment as well as information about availability of the necessary equipment in European institutions, as well as technical recommendations and scientific explanations of parameter extraction procedures.
Work on the last task (provide suggestions on how to characterise electromagnetic properties of the materials under development in the manufacturing projects (FP7 NMP)) resulted in the development of a roadmap for experimental characterisation of metamaterials. This tool (available on the project website) provides a step-by-step guidance on how to determine experimentally what kind of structure is tested and, if this is indeed a new material, how to assess the electromagnetic properties of composite material samples. The following picture illustrates the layout of the road map (only the first step is shown). This roadmap has two versions - one is for non-specialists and the other for experts in the field. In the latter version, additional details are given as well as recommendations are provided for future work on the development of experimental techniques. The road map has accumulated the results of the work performed in this project and, according to the schedule, was finalised at the end of the project. These results have been posted on the project web site and will be promoted by the project participants beyond the project lifetime. Naturally, adoption of the novel advanced characterisation techniques will require extensive discussions in the wide scientific community and it will involve a number of iterations before becoming universally accepted.
WP3 - Access to measurement facilities, computational tools and data banks
(WP leader Dr Vladimir Podlosny, Metamorphose Virtual Institute, Belgium)
This WP organised access for SME and other interested organisations in Europe to the existing measurement, computational and data resources at the public laboratories of the project beneficiaries. Also it facilitated access to other European EM NSM characterisation centres via information management activities and promotional actions. The organised access (not only to the facilities of the project beneficiaries but also to other leading European organisations) was provided via a number of tools developed and posted on the project web site. The WP has collected information about the available facilities and made it accessible in form of well organised and searchable databases published on the web site.
The following laboratories contributed to the facilities database:
- Institut fur Photonik und Quantenelektronik, Karlsruhe University, Karlsruhe, Germany.
- Laboratory of Physical Chemistry, Swiss Federal Institute of Technology Surich, Switserland.
- Institute for Atomic and Molecular Physics, Amsterdam, Netherlands.
- Nanophotonic, Institut of Physics, Faculty of Mathematics and Science, Technical University of Ilmenau, Ilmenau, Germany.
- Nanobiotechnology-Group, Gutenberg Universität, Mains, Germany.
- Physikalisches Institut, Physiksentrum, RWTH, Aachen, Germany.
- Physikalisches Institut, Universitaet Stuttgart, Stuttgart, Germany.
- Centre for Innovation Competence, Institute of Applied Physics, Friedrich Schiller University Jena, Jena, Germany.
- The Institute for Nanotechnology, University of Karlsruhe, Karlsruhe, Deutschland.
- Optoelectronics Research Centre, University of Southampton, Southampton, UK.
- Centre for Solid State Physics and New Materials, Belgrade, Serbia.
- Centre for Surface and Nanoanalytics, Lins, Austria.
- Sentech Instruments GmbH, Berlin, Germany.
- Institute of Applied Physics Friedrich-Schiller-Universität Jena, Jena, Germany.
- Institute for Analytical Sciences, Berlin, Germany.
The laboratory profiles contain also information about access rules currently adopted at each site.
The appropriate facility or computational tool can be found in accordance with the type of measurement or the type of equipment or by the type of material under study. Each facility is described in detail, including the contact information of the local person responsible for organisation of access by external users.
The access tools developed by the ECONAM project were promoted through web-posted news, via review presentations at conferences and review papers describing ECONAM project activities.
WP4 - Dissemination, education, and training
(WP leader Prof. Filiberto Bilotti, University Roma Tre, Italy)
Special efforts and measures are needed to deliver new knowledge, new measurement techniques, and approaches to extraction of effective material parameters. The main current problem in the area of research and development that we addressed by this CSA is that there are no well-developed and commonly accepted characterisation techniques. The recent achievements in electrodynamics of nanocomposites have shown that it is impossible to apply the existing concepts of electromagnetic characterisation of materials to nanocomposites. In the situation when this new knowledge is not properly disseminated, it may lead to negative unpredictable consequences. For example, the old concepts are used as the theoretical foundation of software used in the commercial measuring devices (ellipsometers). This means that in majority of situations the measured parameters cannot be utilised in device design because the physical meaning of the parameters is not clear or even wrongly defined. It is obvious that there is a pressing need to disseminate the latest knowledge in this field and promote creation of commonly accepted characterisation techniques. Furthermore, the users of new nanostructured materials should be educated in the area of electromagnetic characterisation, so that they can use the measured parameters to predict material performance in a particular device.
The dissemination activities are targeted towards: (a) researchers in electromagnetic and material science, (b) industries and SMEs, as well as (c) general public. Next we present the WP results in each of its tasks.
The first task was to organise European School Events on NSM characterisation of advanced electromagnetic materials each year. This work was led by the Metamorphose Virtual Institute and completed successfully. School on 'Fabrication and optical properties of nanostructured metamaterials' was organised in conjunction with the '8th International conference on electrical transport and optical properties of inhomogeneous media' (ETOPIM8) on Crete, Greece, 12-13 June 2009. The illustration shows the home page of that school event.
The ECONAM project contributed to the one-week international school on Fundamentals of Metamaterials Electromagnetics (16-20 November 2009, Levi, Finland), with three (out of four) lecturers provided by the ECONAM project partners.
In the last year of the ECONAM project activities, the project organised a week-long school on experimental electromagnetic characterisation of complex materials and metamaterials. Below is a picture showing the home web page of this event.
All the school events have got most positive feedback from the participants.
The second task was to prepare online and offline web-based electronic courses on NSM characterisation. This work resulted in an extensive video tutorial lecture available for download from the project web site, as well as in an educational section on the web site. In addition, all the lectures presented at the doctoral school events have been recorded as video files or as a set of slides and all these materials have been posted on the doctoral school web site.
The next task was to organise special sessions on electromagnetic characterisation techniques and existing European facilities for NSM at the METAMATERIALS Congress and other conferences.
The main efforts of this CSA were on coordination and support to the European work towards development, testing, and dissemination of methods and tools for electromagnetic characterisation and metrology of nanostructured composite materials (metamaterials). Based on this, for discussions of problems of electromagnetic characterisation of composite materials we have chosen the main forums where experts in this area of nanoscience and material science meet: Metamaterials 2008 (Pamplona) and 2009 (London), Meta'2010 (Cairo), and others. The dissemination efforts were directed to a wider audience including other areas of nanoscience and material science, as well as potential applications of novel electromagnetic properties of nanostructured metamaterials. These conferences include Material research society (MRS) meeting, forum on new materials, electromagnetics in advance applications, and others.
Below we provide some details about the most prominent events.
Metamaterials congress (http://congress2011.metamorphose-vi.org/) organised by the Metamorphose virtual institute (one of the beneficiaries of the ECONAM project) has been one of the main dissemination engines for ECONAM.
A panel session organised by the ECONAM project has been convened at the second congress on 'Artificial electromagnetic materials for microwaves and optics', Metamaterials 2008 held in Pamplona, Spain on 21-26 September 2008. The session entitled 'Theoretical issues and practical aspects of metamaterial characterisation' has been organised by Prof. A. Schuchinsky (partner of ECONAM) and Prof. R. Mittra, Pennsylvania State University, USA. The panellists were the following:
- Prof. Sergei Tretyakov, Helsinki University of Technology, Finland (ECONAM partner).
- Prof. Allan Boardman, University of Salford, UK.
- Prof. Ricardo Marques, University of Seville, Spain.
- Prof. Stefan Linden, Karlsruhe University, Germany (ECONAM partner).
- Prof. Yang Hao, Queen Mary University of London, UK.
- Prof. Raj Mittra, Pennsylvania State University, USA.
- Prof. Alex Schuchinsky, Queen's University Belfast, UK (ECONAM partner).
The panel session attended by more than 100 participants of the congress comprised brief presentations by the panellist followed by the extensive interactive discussion involved both the panellists and audience. The session materials are available at the ECONAM website. A special session entitled 'Progress of the ECONAM project' was organised at the third international congress on 'Advanced electromagnetic materials in microwaves and optics' - Metamaterials 2009, held in London, UK on 30 August - 4 September 2009. In the ECONAM special session there was massive participation of NMP audience, especially of experts in the particular field of this CSA (electromagnetic characterisations of nanostructured materials).
Here is the list of presented papers: Henrik Wallén, Henrik Kettunen, Ari Sihvola, Helsinki University of Technology (AALTO), Finland, Applicability of classical mixing rules: from positive to negative parameters Costas Soukoulis, J. Shou, M. Kafesaki, Th. Koschny, Foundation for Research and Technology Hellas (FORTH), Greece, Weakly and strongly coupled optical metamaterials Chris Fiets, Dmitriy Korobkin, Burton Neuner, Department of Physics, Chihui Wu, Gennady Shvets, Department of Physics, The University of Texas at Austin, USA, Characterisation of plasmonic metamaterials using effective parameters Constantin Simovski, Helsinki University of Technology (AALTO), Finland, On the locality of Drude transition layers for metamaterials Alexey Vinogradov, Alexander Merslikin, ITAE, Russia; Said Souhdi, Laboratoire de Génie Electrique de Paris LGEP-Supélec, France, On non-Maxwellian boundary conditions for metamaterial interface.
As is seen from this list, participation of experts from outside the ECONAM participants was ensured, and it was the key for the meeting success.
In 2010, ECONAM organised a special ECONAM session at conference META 2010 (Cairo). This event was very well attended by experts in nanoscience and material science, working on electromagnetic properties of nanostructured materials. At this session, intermediate results of WPs 1,2 have been disseminated, and, most important, the members of ECONAM expert consultative groups met each other and other distinguished experts in the fields, which resulted in decisive contributions to the analysis and recommendations presented in updates to a number of deliverables.
The session was introduced by a keynote presentation by A. Vinogradov (ECONAM partner ITAE) entitled 'Homogenisation of metamaterials: bulk properties and boundary conditions'. In this talk the pitfalls of different approaches of introduction of effective constitutive parameters were considered. Today we encounter a situation that remembers one in the beginning of the twenty century. It was the time of a crisis of classical mechanics, which finished with creation of relativistic theory and quantum mechanics. Now we go through the crisis of classical electrodynamics of condensed matter developed by Maxwell, Heaviside and Lorentz. Indeed, as in the beginning of twenty century, we observe an increase of experimental results that can hardly be explained with the existent theories.
Here is the list of the other papers presented at the session:
- Yu. E. Lozovik (ITAE), Electromagnetic characterisation of graphene and graphene based nanostructures.
- A. G. Schuchinsky (QUB), A. Vallecchi, A.P. Shitvov and F. Capolino, Resonance transmittance in metamaterials made of stacked arrays of dogbone shaped conductor pairs.
- S. Larouche and D. R. Smith, Quantifying the nonlinear susceptibility of metamaterials.
- D. Mogilevtsev, F. A. Pinheiro, R. R. dos Santos, S. B. Cavalcanti and L. E. Oliveira, Anderson localisation in disordered dispersive metamaterials.
- M. H. Belyamoun, A. Bossavit and S. Souhdi, Frequency-dependent homogenisation of split-ring arrays.
- R. Kotynski, T. Stefaniuk, A. Pastusscsak, Sub-wavelength diffraction-free imaging in low-loss metal-dielectric multilayers.
The special sessions organised by ECONAM provided an important and timely review of the state-of-the-art in characterisation of artificial electromagnetic materials, which was later recorded in updates to ECONAM deliverables and on its web site tools. The papers have been presented by the experts in the field, who addressed the current issues on the definition and determination of the physical parameters suitable for the meaningful description of the metamaterial properties. The sessions represented also an important place where the latest results on the characterisation of nanostructured materials have been discussed and where the experts in the field got together and compared the different approaches used.
Actually this activity was not only a part of work on dissemination - these special sessions were of key importance for the work of the expert consultative groups (WPs 1,2). At these sessions the preliminary results of the expert group work were discussed within the wide international scientific community, and here the experts of the project collected information on the latest developments in the field of their expertise, which was then used to update and develop the analytical reviews and recommendation documents of the ECONAM project. As explained above, due to the Seventh Framework Programme (FP7) financial rules it was not possible to involve more external experts into the project consultative groups directly, and these special sessions were successfully used as a tool to dramatically widen the scope of the project activities due to participation of experts not directly involved in the ECONAM project.
The task on writing the monograph on electromagnetic characterisation of nanostructured materials has resulted in the tutorial overview of approaches to electromagnetic characterisation of nanostructured materials. This extensive document (79 pages) has been formed and edited as the combined and structural output of the whole work of the Expert Consultative Groups during the whole project life. In addition, it contains an introductory chapter on basics of electromagnetic properties of materials. The book is accessible for non-specialists in the field, with appropriate references to original publications for the expert reader. Because this cumulative book was finalised (according to the work plan) at the end of the project, at this stage it could be disseminated only via the project web site. However, the ECONAM consortium is considering possible publication of this text as a book.
The last task of this WP was an educational event for the new FP7 NMP projects on manufacturing of metamaterial structures. The event was organised in December 2009 in Brussels, and was well attended by the beneficiaries of the respective NMP projects. The ECONAM project has organised the event and delivered a set of tutorial lectures not only on the topic of the CSA (electromagnetic characterisation of nanostructured materials) but also tutorials on the basics of electromagnetic properties of materials and their description. Below we present the first slides of the three main lectures.
WP5 - Information and communication support for research and dissemination
(WP leader Dr Vladimir Podloshny, Metamorphose Virtual Institute, Belgium)
Starting from the project outset till its very last days the project web site http://econam.metamorphose-vi.org has been continuously evolving and developed as the main education and dissemination tool of the project. The web site structure has been constantly advanced. Each new deliverable or its update has been promptly posted on the web site and integrated in the overall structured and logical informational and educational skeleton. At the later stages, the web site received an additional menus 'for beginners', 'for specialists' and 'for industrialists', with separate introductions and guidance pages targeted for each of these three categories. The menu 'characterisation' leads the reader step-by-step along the learning process, logically introducing the analytical and recommendation documents generated by the project.
The picture below illustrates the site popularity grows during the first project year.
Promotion of the project website took place at several scientific and technical meetings as well as on a number of commercial and public websites. The key persons participating in ECONAM promoted the site via their personal web sites. Links have been made also from participants' departments and laboratories web pages. The web site link was promoted via review presentations about ECONAM activities, both via the abstracts and proceedings publications and during talks. Promotional video was made and on Youtube: http://www.youtube.com/watch?v=RUar3D-2nTc.
The potential impact
The main impact of this CSA is in the development and dissemination of the novel techniques for electromagnetic characterisation of nanostructured materials and preparing the basis for future standards in the field of nanomaterials characterisation in terms of the electromagnetic parameters. This will complement the known techniques for characterisation in terms of particle and reactivity by developing unified approaches to characterisation in terms of permittivity, permeability, chirality parameter, surface impedance, grid impedance and similar descriptions. These parameters will be able to characterise not only bulk materials, but also thin layers and interface behaviour. Acceptance of these new methods for electromagnetic characterisation will have dramatic impact on nanotechnology applications especially in telecommunications, imaging, detection, and sensors.
The expected long-term impact will be adoption of common measurement tools for the electromagnetic characterisation of nanostructured materials. Such unified measurement methods and tools and the parameter retrieval procedures will be very important for the European industry as this will allow them to use the standard characterisation procedures for applications that involve nanostructured materials. This project has brought a new level of cohesiveness to the field of electromagnetic characterisation of nanostructured materials. Coordination of the experimental measurement techniques and metrology standards used for characterisation of nanostructured materials will result in reliable and reproducible material development efforts which are essential for future applications of nanostructured artificial electromagnetic materials. The benefits for industry and particularly SMEs will include access to the unique equipment and expertise that would ordinarily be too expensive in term of time and cost.
The development and broad adoption of the new characterisation techniques is a long process, but even now we can observe that the impact of ECONAM project is quite visible and tangible. In the scientific and technical community there is much more awareness of difficulties and pitfalls in the conventional characterisation techniques when one applies them to novel complex nanostructures. The analysis of the most recent literature shows that more and more papers attempt to fill the gaps of knowledge in this field and propose new advanced characterisation methods, applicable to metamaterials. We are pleased to see the influence of our efforts on these growing international developments.
The ECONAM project web site is now acting as a virtual European facility for electromagnetic characterisation of nanostructured composite materials, which offers comprehensive information on the well-established, tested, and widely disseminated measurement techniques and methodologies for the material parameter retrieval as well as the detailed knowledge on pitfalls, problematic issues, and novel approaches suitable for emerging complex nanostructured materials. The web site also provides a mechanism for sharing measurement facilities and providing quality metrology services for the industries and SMEs.
Potential impact:
The main impact of this CSA is in the development and dissemination of the novel techniques for electromagnetic characterisation of nanostructured materials and preparing the basis for future standards in the field of nanomaterials characterisation in terms of the electromagnetic parameters. This will complement the known techniques for characterisation in terms of particle and reactivity by developing unified approaches to characterisation in terms of permittivity, permeability, chirality parameter, surface impedance, grid impedance and similar descriptions. These parameters will be able to characterise not only bulk materials, but also thin layers and interface behaviour. Acceptance of these new methods for electromagnetic characterisation will have dramatic impact on nanotechnology applications especially in telecommunications, imaging, detection, and sensors.
The expected long-term impact will be adoption of common measurement tools for the electromagnetic characterisation of nanostructured materials. Such unified measurement methods and tools and the parameter retrieval procedures will be very important for the European industry as this will allow them to use the standard characterisation procedures for applications that involve nanostructured materials. This project has brought a new level of cohesiveness to the field of electromagnetic characterisation of nanostructured materials. Coordination of the experimental measurement techniques and metrology standards used for characterisation of nanostructured materials will result in reliable and reproducible material development efforts which are essential for future applications of nanostructured artificial electromagnetic materials. The benefits for industry and particularly SMEs will include access to the unique equipment and expertise that would ordinarily be too expensive in term of time and cost.
The development and broad adoption of the new characterisation techniques is a long process, but even now we can observe that the impact of ECONAM project is quite visible and tangible. In the scientific and technical community there is much more awareness of difficulties and pitfalls in the conventional characterisation techniques when one applies them to novel complex nanostructures. The analysis of the most recent literature shows that more and more papers attempt to fill the gaps of knowledge in this field and propose new advanced characterisation methods, applicable to metamaterials. We are pleased to see the influence of our efforts on these growing international developments.
The ECONAM project website is now acting as a virtual European facility for electromagnetic characterisation of nanostructured composite materials, which offers comprehensive information on the well-established, tested, and widely disseminated measurement techniques and methodologies for the material parameter retrieval as well as the detailed knowledge on pitfalls, problematic issues, and novel approaches suitable for emerging complex nanostructured materials. The web site also provides a mechanism for sharing measurement facilities and providing quality metrology services for the industries and SMEs.
List of websites: http://econam.metamorphose-vi.org/
