New Anisotropic Organic Conductors and Superconductors
Main researcher
: TOMIĆ, SILVIA (65594) Assistants
HAMZIĆ, BOJANA (61314)
COOPER, JOHN-ROBERT (7044)
SMONTARA, ANA (119684)
GLADIĆ, JADRANKO (86441)
BILJAKOVIĆ, KATICA (76732)
PRESTER, MLADEN (68441)
DOLANSKI-BABIĆ, SANJA (188231)
BIŠKUP, NEVENKO (179286)
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
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
Name of project
: CI1*-CT90-0863CD Organic Conductors and
Superconductors Name of institution: University of Copenhagen City: Copenhagen, Danska
Name of project
: CI1*-CT90-0863CD Organic Conductors and
Superconductors Name of institution: University of Stuttgart City: Stuttgart, Njemačka
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
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
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
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
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
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
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
Name of institution
: Universite de Montpellier II Type of institution: University/Faculty Type of cooperation: Joint publishing of scientific papers City: 34095 - Montpellier, Francuska
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
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
Name of institution
: Prirodoslovno-matematički fakultet Type of institution: University/Faculty Type of cooperation: Joint publishing of scientific papers City: 10000 - Zagreb, Croatia
Name of institution
: University of Copenhagen Type of institution: University/Faculty Type of cooperation: Joint publishing of scientific papers City: Copenhagen, Danska
Name of institution
: University of Cambridge Type of institution: University/Faculty Type of cooperation: Systematic exchange of experts City: Cambridge, Engleska
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
Name of institution
: Ecole Politechnique Federale de Lausanne Type of institution: University/Faculty Type of cooperation: Systematic exchange of experts City: 1001 - Lausanne, Switzerland
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
Name of institution
: Institut Rudjer Bošković Type of institution: State institute Type of cooperation: Systematic exchange of information City: 10000 - Zagreb, Croatia
OTHER ACHIEVEMENTS
Name
: Uredjaj za automatsko dc mjerenje velikih otpora u širokom
temperaturnom intervalu Type of achievement: Technology Authors: N.Biškup, S.Tomić
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
Name
: Uredjaj za mjerenje malih signala ac naponskih oscilacija
u jakim dc poljima Type of achievement: Technology Authors: N.Biškup, S.Tomić
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
Name
: Uredjaj za automatsko ac mjerenje otpora u širokom
temperaturnom intervalu Type of achievement: Technology Authors: N.Biškup, S.Tomić Other information about the project.