SVIBOR - Project code: 1-03-054

MINISTRY OF SCIENCE AND TECHNOLOGY

Strossmayerov trg 4, HR - 10000 ZAGREB
tel.: +385 1 459 44 44, fax: +385 1 459 44 69
E-mail: ured@znanost.hr

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Project code: 1-03-054


New Anisotropic Organic Conductors and Superconductors


Main researcher: TOMIĆ, SILVIA (65594)



Assistants
Type of research: basic
Duration from: 01/01/91. to 12/31/94.

Papers on project (total): 116
Papers on project quoted in Current Contents: 65
Institution name: Institut za fiziku, Zagreb (35)
Department/Institute: Physics of Metals II
Address: Bijenička 46, POB 304
City: 10000 - Zagreb, Croatia
Communication
Phone: 385 (0)1 271-211
Fax: 385 (0)1 421-156
E-mail: stomic@ifs.hr

Summary: During the last ten years chemists, crystallographers and physicists in many universities and some industrial laboratories have worked together in developing a new interdisciplinary research field: the synthesis and study of new organic compounds which are good electrical conductors. These materials possess unusual physical properties due to their extremely anisotropic (low dimensional) band structure. Dependent on the pressure, there are phase transitions at low temperatures associated with the formation of different ground states: superconducting (SC, Tc(max)=12K), charge-density wave (CDW, Tc=20-100K) and spin-density wave (SDW, Tc=10K). Although much progress has been made in a short time, the nature of SC state and the factors determining Tc and the critical current are still not understood. The materials with SDW (and CDW) are ideal systems to study novel mechanisms of collective electrical transport (here we point out that the "classical" SC as a collective mechanism has been known already for long time and well explained in the framework of the BCS theory) as well as novel quantum phenomena (quantized Hall effect, quantum oscillations). The continuous efforts of organic chemists are constant source of new materials with extremely reach phase diagrams. Here we point out that according to the report of american National Research Council (National Academy Press, 1986) among the most interesting advances in condensed-matter physics that occured in the 70s and 80s are effects of reduced dimensionality, charge-density waves, quantized Hall effect and disorder. This project comprises also some aspects of these topics. Novel oxide superconductors (Tc=100K) have anisotropic band structure and therefore also belong to the class of the systems of reduced dimensionality. Small changes of their chemical composition lead to important changes in their properties. Similarly to organic materials, the importance of the electron-electron interaction are emphasized, as well as the proximity of SC and SDW phase. Although many properties of these materials are already known, lot of them are not well established caused by synthesis problems. Consequently, in order to understand the mechanism of the high temperature superconductivity, the measurements of the high quality and precision are needed.

Keywords: low-dimensional conductors, organic conductors, organic superconductors, high-temperature superconductors, spin-density waves, charge-density waves, disorder, magnetoresistance, Hall effect, quantized Hall effect, low temperatures, quantum oscillations, nuclear magnetic resonance, electron spin resonance, electrical resistivity, non-linear electrical conductivity, electron-electron interactions, imperfect nesting, specific heat, glassy behaviour

Research goals: The aim of the project is to achieve better understanding and toreveal novel phenomena in the systems with the reduceddimensionality. The projecthas essentially four different objectives. First, we will try toreach a clearer understanding of the open problems related tosuperconductivity in the novel anisotropic materials (organic andoxide systems). Second, we will study new quantum phenomena inthe spin density wave ground state. Third, we will study indetail properties of the novel mechanism of the collectiveelectrical conduction by the sliding of SDW (and CDW), and we will also study the dynamics of the pinned SDW. Fourth, we will study neworganic conductors and search for the phase transitions andinteractions which define the electrical transport. The specialobjective in the study of the oxide high-temperaturesuperconductors is to achieve high-quality measurements on thehigh-quality samples, in particular single crystals. The criticalanalysis of the obtained results will be done in the framework ofthe actual theoretical models. We will also try, through theconstant collaboration with theoretical physicists, to stimulatenovel theoretical advancements. The whole research will becarried out in the constant collaboration with our foreignpartners. The results will be published in internationalscientifique journals. The proposed research is a contribution tofundamental science in an interdiscplinary field linking solidstate physics and organic chemistry.


COOPERATION - PROJECTS


  1. Name of project: CI1*-CT90-0863CD Organic Conductors and Superconductors
    Name of institution: Laboratoire de Physique des Solides, Universite de Paris-Sud (Le Centre National de la Recherche Scientifique)
    City: 91405 - Orsay, Francuska

  2. Name of project: CI1*-CT90-0863CD Organic Conductors and Superconductors
    Name of institution: University of Copenhagen
    City: Copenhagen, Danska

  3. Name of project: CI1*-CT90-0863CD Organic Conductors and Superconductors
    Name of institution: University of Stuttgart
    City: Stuttgart, Njemačka

  4. Name of project: CI1*0568-C (EDB) Properties of Single Crystals of High Temperature Superconductors
    Name of institution: Laboratoire de Physique des Solides, Universite de Paris-Sud (Le Centre National de la Recherche Scientifique)
    City: 91405 - Orsay, Francuska

  5. Name of project: CI1*0568-C (EDB) Properties of Single Crystals of High Temperature Superconductors
    Name of institution: The Josef Stefan Institute
    City: Ljubljana, Slovenija

  6. Name of project: CI1*0568-C (EDB) Properties of Single Crystals of High Temperature Superconductors
    Name of institution: Le Commissariat a l'Energie Atomique (Institut de Recherche Fondamentale)
    City: 38042 - Grenoble, Francuska

  7. Name of project: CI1*0568-C (EDB) Properties of Single Crystals of High Temperature Superconductors
    Name of institution: The Imperial College of Science, Technology and Medicine
    City: London, Engleska

  8. Name of project: bilateralni-CNRS Single-Particle Properties and Collective Mechanism for the Electrical Conductivity in Organic Conductors
    Name of institution: Laboratoire de Physique des Solides, Universite de Paris-Sud
    City: 91405 - Orsay, Francuska


COOPERATION - INSTITUTIONS


  1. Name of institution: Laboratoire de Physique des Solides, Universite de Paris-Sud
    Type of institution: University/Faculty
    Type of cooperation: Joint project
    City: 91405 - Orsay, Francuska

  2. Name of institution: Centre des Recherches sur les Tres Basses Temperatures
    Type of institution: State institute
    Type of cooperation: Systematic exchange of information
    City: 38042 - Grenoble, Francuska

  3. Name of institution: Universite de Montpellier II
    Type of institution: University/Faculty
    Type of cooperation: Joint publishing of scientific papers
    City: 34095 - Montpellier, Francuska

  4. Name of institution: Service des Champs Magnetiques Pulses, Institut National des Sciences Appliquees
    Type of institution: State institute
    Type of cooperation: Systematic exchange of information
    City: 31077 - Toulouse, Francuska

  5. Name of institution: Department of Physics, University of Southern California
    Type of institution: University/Faculty
    Type of cooperation: Joint publishing of scientific papers
    City: Los Angeles, USA

  6. Name of institution: Prirodoslovno-matematički fakultet
    Type of institution: University/Faculty
    Type of cooperation: Joint publishing of scientific papers
    City: 10000 - Zagreb, Croatia

  7. Name of institution: University of Copenhagen
    Type of institution: University/Faculty
    Type of cooperation: Joint publishing of scientific papers
    City: Copenhagen, Danska

  8. Name of institution: University of Cambridge
    Type of institution: University/Faculty
    Type of cooperation: Systematic exchange of experts
    City: Cambridge, Engleska

  9. Name of institution: Laboratoire de Spectrometrie Physique, Universite J.Fourier
    Type of institution: University/Faculty
    Type of cooperation: Systematic exchange of experts
    City: 38042 - Grenoble, Francuska

  10. Name of institution: Ecole Politechnique Federale de Lausanne
    Type of institution: University/Faculty
    Type of cooperation: Systematic exchange of experts
    City: 1001 - Lausanne, Switzerland

  11. Name of institution: State University of New York at Stony Brook
    Type of institution: University/Faculty
    Type of cooperation: Systematic exchange of experts
    City: Stony Brook, USA

  12. Name of institution: Institut Rudjer Bošković
    Type of institution: State institute
    Type of cooperation: Systematic exchange of information
    City: 10000 - Zagreb, Croatia


OTHER ACHIEVEMENTS


  1. Name: Uredjaj za automatsko dc mjerenje velikih otpora u širokom temperaturnom intervalu
    Type of achievement: Technology
    Authors: N.Biškup, S.Tomić

  2. Name: Uredjaj za automatsko mjerenje otpora i magnetootpora u širokom temperaturnom području
    Type of achievement: Technology
    Authors: M.Basletić, A.Hamzić, B.Hamzić, S.Tomić

  3. Name: Uredjaj za mjerenje malih signala ac naponskih oscilacija u jakim dc poljima
    Type of achievement: Technology
    Authors: N.Biškup, S.Tomić

  4. Name: Uredjaj za automatsko mjerenje dielektričnog odziva u frekventnom području 20Hz-1MHz i širokom temperaturnom intervalu
    Type of achievement: Technology
    Authors: N.Biškup, A.Omerzu, S.Tomić

  5. Name: Uredjaj za automatsko ac mjerenje otpora u širokom temperaturnom intervalu
    Type of achievement: Technology
    Authors: N.Biškup, S.Tomić

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Last update: 10/08/95
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