national institute of materials physics annual report 2012

NATIONAL INSTITUTE OF MATERIALS PHYSICS

ANNUAL REPORT 2012 1

National Institute of Materials Physics (Institutul National de Cercetare-Dezvoltare pentru Fizica Materialelor)

DIRECTORATE Director: Dr. Lucian Pintilie Scientific Director: Dr. Florin Vasiliu

ADDRESS P.O. BOX MG – 7 Bucharest – Magurele / ROMANIA Tel. (+4) 021 369 01 85 Fax (+4) 021 369 01 77

E-Mail L. Pintilie: [email protected] F. Vasiliu: [email protected]

WWW http: //www.infim.ro

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Table of Contents Preface .............................................................................................................................................4 Laboratories ...................................................................................................................................7 Personnel .......................................................................................................................................12 List of Personnel .......................................................................................................................13 Visiting Guests ..........................................................................................................................18 Ph.D. Theses ..............................................................................................................................19 Awards.......................................................................................................................................20 Honorary Membership ............................................................................................................21 Publications and Presentations ...................................................................................................24 Books .........................................................................................................................................25 Journals .....................................................................................................................................26 Conference Proceedings ...........................................................................................................60 Contributed Presentations .......................................................................................................63 Invited Lectures ........................................................................................................................85 Selected Results ............................................................................................................................89 Condensed Matter Physics at Mesoscale ................................................................................89 Nanoscale Physics ...................................................................................................................132 Potential Applications ............................................................................................................157 Patents and Patent Requests .....................................................................................................189 Seminars......................................................................................................................................191 Events ..........................................................................................................................................196 International Cooperation.........................................................................................................212 NIMP Funding ...........................................................................................................................219

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PREFACE

2012 was a successful year for the National Institute of Materials Physics, especially from the point of view of the scientific output. Thus NIMP has published 180 papers in ISI journals which is equivalent with a cumulated impact factor of 377.2, the highest in the institute history. We must mention that in next couple of months, some other publications will be added at this record (taking into account some delayed journal issues) and also that now other 33 papers are already published or accepted for 2013. In Fig. 1 it is shown the NIMP output in the last five years which prove the consolidation of the scientific performance especially by comparison with years 2009, 2010 when the impact factor was roughly half from the nowadays value.

Paper Number Cumulative Impact Factor

200

400

NIMP OUTPUT 2008-2012

Paper Number

160

300

140

120 200 100

Cumulative Impact Factor

180

80 2008

2010

2012

A

Fig. 1 4

Other important observation is related to the tendency of publication in higher impact factor journals (Fig. 2). If in the years 2009-2010, the cumulated impact factor of journals with FI>2 was 75 and 120, respectively, in 2011 this increased to 200 and to 240 in 2012 (even without adding the two papers published in very high impact factor journals-one of 54 in 2011 and other 36 in 2012). Therefore, about 60% from cumulated impact factor is now obtained only from papers published in the very prestigious journals.

NIMP Impact Factor Distribution 2008-2012 90 80 70 60 50 40 30 20 10 0

2008 2009 2010 2011 2012 0-1.0

1.0-2.0

2.0-3.0

3.0-4.0

4.0-5.0

>5.0

Fig. 2

In 2012 a number of 176 contributed presentations (invited, talk or poster) have been selected to be communicated at international conferences, congresses or workshops. Research work was dedicated to a high number of projects such as: 3 CORE projects, 5 projects UEFISCDI Module III, 13 IDEAS-PCE projects, 11 HUMAN RESOURCES projects, 2 IDEAS-PCCE projects as coordinator, 2 IDEAS-PCCE projects as partner, 3 IFA-CEA projects, EURATOM 6 projects, 4 PARTNERSHIP projects as coordinator and other 13 as partner. NIMP continued to develop new international collaborations with research institutions from whole word. In 2012 NIMP has continued or started 2 FP7 projects, a CERN collaboration, 2 projects Romanian Swiss Research Program RSRP, 3 projects with Commissariat de l”Energie Atomique (CEA), 1 project with Agence Nationale de Recherche (ANR), other 7 European-funded projects, 6 inter-governmental agreements and 12 bilateral cooperation with foreign institutes or universities. Several events with international participation were organized in 2012, among which the workshop "Advanced workshop on solar energy conversion" ( 21 - 23 May 2012.), the 7th International Conference on Advanced Materials, ROCAM 2012, 28-31 August 5

2012, Brasov, Romania and two exploratory workshops entitled: ”Theory and experiment in surface, interface and nanoparticle physics” and “Materials in extreme conditions: processing, characterization and applications” in the framework of the conference “Diaspora in Romanian Research and High Education-“Seeds for the Future “ (25-28 September 2012) 2012 was a challenging year for NIMP. The institute has been evaluated by an international panel who has decided that the institute will be certified for research (certification level: A +). We think that the future institutional funding will depend entirely on the result of this evaluation exercise. In summary, the NIMP team is ready to face the challenges of the present in order to consolidate the leading position of the institute in the national research system and his excellent visibility at international level.

Dr. Lucian Pintilie General Director

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Laboratories

10. Laboratory of Multifunctional Materials and Structures The laboratory is dedicated to the research of oxidic materials and nanostructures with an emphasis on functionality and applications. A wide range of properties of the materials are studied, including here dielectric , ferroelectric, piezoelectric, optic and transport, for bulk materials, thin films and nanostructures. There are two main research directions: 1. Synthesis and characterization of nano-objects (e.g. nanowires, nanotubes, nanocylinders, nanospheres) and of devices or applications including such low dimensional structures (e.g. nanowire diodes, photodetectors, OLED, ultraminiaturised light emitting structures, targeted drug delivery vectors). 2. Synthesis and characterization of bulk materials and thin films with ferroelectric, piezoelectric or multiferoic properties for applications in various fields such as information technology, communications, microwave technology. The activities in the laboratory are well balanced between synthesis and characterization of materials. The main methods of preparation employed are both physical and chemical: pulsed laser deposition and magnetron sputtering, sol-gel, electrodeposition and chemical bath deposition, chemical synthesis and various polymerization approaches. In this way materials with different characteristic sizes are obtained, such as bulk ceramics, thin films and multilayers (including MOS structures), semiconductor and metal nanowires and polymer nanofibers, simple structure or core shell nano-particles of various materials ranging from polymers to semiconductors or magnetic oxides. Characterization techniques cover a wide range from optical to transport properties, from structure to microwave properties or magnetism and are basd on a high quality infrastructure. Examples of techniques unique in the area are: deep level transient spectroscopy, near field phtotoluminescence spectroscopy, cathodoluminescence, microwave characterization of materials on a wide range and up to far infrared. The structure of personnel is also well balanced, 24 physicist and 6 chemists representing the research personnel of the laboratory out of which 11 young assistants being hired in the last few years.

20. Laboratory of Magnetism and Superconductivity The laboratory is devoted to research in the field of materials with magnetic or superconducting properties and related electronic phenomena. The research process covers all the steps from preparation (powder, bulk, ribbons, thin films or nanostructures), going through basic physical characterizations, and ending with in-depth analysis of the magnetic dependent and superconducting properties. The laboratory is composed by two groups of specific activities related to electronic correlations and magnetism and respectively, superconductivity. As main research directions are to be mentioned: size effects and interactions in nanoparticulate systems and nanocomposites, interfacial interactions and surface electronic/spin configurations in layered nanosystems, molecular magnets, phase 7

transitions and electron correlations in functional materials, vortex dynamics in high-Tc superconductors, MgB2 for practical applications, composite superconductors, exotic superconductors (iron-based pnictides, non-centro-symmetric superconductors). The presently available experimental facilities allow the complex processing and investigation of the mentioned systems as well as the understanding the basic interaction mechanisms at the microscopic level, by using first principles atomistic modeling and simulation of materials within the Density Functional Theory (DFT) framework, on specially assigned computer clusters. The magnetic and superconducting structures are prepared by various technologies, like mechanical attrition, melt spinning, microwave annealing, spark plasma & hot press sintering, radiofrequency sputtering, chemical routes, etc. Subsequent processing via thermal treatments (assisted or not by applied magnetic fields) or via gas reaction control can be also managed. The structural and morphological characterization of the samples and a large field of magnetic, thermodynamic and transport properties are studied by Physical Properties and Magnetic Properties Measurement systems (PPMS, MPMS-SQUID), Vibrating Sample and Magneto-Optic Kerr effect magnetometry (VSM and MOKE), DSC/DTA as well as Laser Flash Calorimetry. The declared purpose of understanding and controlling the electronic phenomena and spin configurations is enhanced by the whole range of Mössbauer spectroscopies (the only institute in Romania), from temperature /field dependent Mossbauer spectroscopy, to the surface/ interface sensitive Conversion Electron Mössbauer Spectroscopy (CEMS).

Spark Plasma Sintering (left), MPMS (middle) and PPMS (right) systems

30. Laboratory of Nanoscale Condensed Matter There are 3 reseach groups in the laboratory of Nanoscale Condensed Matter Physics: SITSC-XESD team ( Surfaces, interfaces, thin films and single crystals. X-ray / electron spectroscopies and diffraction), Si- and Ge –based nanomaterials and Nanostructures team and the Theoretical Physics group. The main activities of the SITSC-XESD group are centred on the development and complex studies of new materials, heterostructures, surfaces and interfaces. The group utilizes and maintains several widely used installations of NIMP: (i) a surface and interface science cluster composed by a molecular beam epitaxy (MBE), a scanning tunneling microscopy (STM) and a spin- and angle-resolved photoelectron spectroscopy (SARPES). A non-negligible amount of activity is dedicated to the development of analysis methods, starting from the theory of quantitative assessment to the adjustment of the experimental 8

conditions. The group also provides unique expertise at national level in two very demanded fields: X-ray diffraction and X-ray photoelectron spectroscopy. Also, this is practically the unique group in the country concentrated on surface and interface science, working in real ultrahigh vacuum (UHV, 10-10 to 10-11 mbar). An MBE setup is installed and works currently. The X-ray diffraction expertise is also boosted by novel developments in the XRD basic theory and data analysis, often implemented in widely used XRD analysis codes, which emerged also from the SITSC-XESD group. The Si- and Ge –based nanomaterials team is working in the field of nanostructured semiconductors with applications in nanoelectronics, photovoltaics and sensors. The group studies: • Films of Si nanodots embedded in amorphous SiO2 matrix: (i) preparation; (ii) investigation of microstructure, electrical transport, phototransport, and photoluminescence with the aim of capturing quantum confinement effects; (iii) modelling of nanoparticle energy structure. • GeSiO-based nanostructures: (i) preparation of Ge nanoparticles embedded in a-SiO2 matrix, by magnetron sputtering and sol-gel methods; (ii) investigation of electrical behaviour and phototransport (experiment and modelling), photoluminescence and Hall effect. • Electrical processes in carbon nanotubes based structures. • Percolation phenomena: evidenced in carbon nanotubes based structures, Si nanodots embedded in amorphous SiO2 matrix and nanocrystalline porous Si. • Trapping phenomena in Si-based nanostructures: stress-induced traps. • The Theoretical Physics Group studies quantum transport phenomena in mesoscopic systems and provides phenomenological models and reliable descriptions of various effects observed in transport measurements.The main research topics cover several timely and challenging issues of mesoscopic transport: the transient transport regime in nano-devices, the mesoscopic Kondo and Fano-Kondo effects, controlled and intrinsic dephasing in mesoscopic interferometers, Coulomb drag and quantum ratchet effects in parallel quantum dots, spin interference in Rashba rings. 40. Laboratory of Optical Process in Nanostructured Materials The research activity in this laboratory is focused on the study and characterization by optical methods of the nanocomposites and nanostructured materials. Other research topics regard the preparation and characterization of semiconducting nanometric structures, of electrochemical synthesis of polymers with special properties as well as the synthesis and characterization of calcogenide glasses. The main equipment’s used to optical characterization of investigated materials are: UV-VIS-NIR spectrometer (Lamda 950 model, Perkin Elmer), FTIR spectrophotometer (Vertex 70, Bruker), FTIR imaging microscope (Perkin Elmer), FTRaman spectrometer (RFS 100/S model, Bruker), confocal Raman spectrometer (T64000 model, Horiba Jobin Yvon) equipped with Ar and Kr lasers, Scanning Near-Field Optical Microscope and Atomic Force Microscope (Nanonics), a fluorolog (3.2.2.1 model, Horiba Jobin Yvon), thermoluminescence reader (TLD 3500 model, Harshaw), experimental setup for photoconductivity studies and solar simulator (LOT Oriel). Other equipment used to characterization and/or preparation of materials are: broadband dielectric spectroscopy 9

system (Novocontrol), drop shape analysis (DSA 100 model, Kruss), the film evaporation system for organic materials research “Spectros”, Langmuir –Blodgett systems (KSV 5000 model), spin coater (KW-4A model, Chemat) and a potentiostat/galvanostat (Voltalab 80 model, Radiometer Analytical). The main applications reported by this laboratory are in the field of the non-linear optic (as shown in Fig. 1), superhydrophobic textiles, the sensors, batteries and supercapacitors as well as energy conversion (dye-sensitized solar cells).

Fig.1 Anomalous anti-Stokes Raman emission at λexc=514.5 nm of LiNbO3 in three morphological forms: (a) single crystal, (b) platelet made from LiNbO3 powder compressed no hydrostatically at 0.58GPa and (c) micrometric (