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Contenido archivado el 2022-12-23

Electron quantum liquids and quantum solids of reduced dimensionality in molecular organic and inorganic host lattices

Objetivo

The main objective of this project is to investigate experimentally and theoretically the physics inherent in strongly correlated electron systems, which are on the border between quantum liquids and quantum solids. The studies focus on molecular organic crystals because of the higher mobilities and larger interaction strength potentially achievable in electron systems in these host lattices. A primary task of this project is to develop high mobility metal-oxide-semiconductor (MOS) structures on the surface of pure crystals of the organic donor molecules, thus enabling the investigations under "electrical doping" of the surface layer by applied electric field. In order to study the effect of the electron-electron interaction, materials with moderate (well described by Fermi liquid, FL, theory) to extremely strong interaction strengths will be investigated. The study will also include strongly interacting quasi-one dimensional (Q1D) systems, for which the FL approach generally fails.

The parameters and the interaction strength in the carrier systems studied will be varied in three independent ways;
(a) By "chemical doping": charge-transfer salts (CTS) will be made by chemical combination of the donor molecules with suitable anions;
(b) By external pressure: the effective dimensionality of the CTS will be varied using hydrostatic pressure;
(c) By "electrical doping" which will be accomplished by applying an electric field at the surface of the crystals of the donor molecules. In order to establish the properties associated with non-FL behaviour, the results of these studies will be compared with the knowledge base accumulated in studies of correlated electrons in inorganic semiconductors (Si and GaAs) and crystalline organic molecular metals of reduced dimensionality.

The research activity will thus develop along the two major directions:
1)Synthesis, growth, characterization of promising organic compounds and fabrication of organic MOS structures on their basis. The families of organic crystals will include both, aromatic crystals (tetracene, pentacene, coronen), and molecular crystals [BEDT-TTF, TCNQ, TMTSF, M(dddt)2, donor-acceptor complexes of fullerene C60 with organic donors and solvents of different nature];
2)Experimental and theoretical investigations of the electron systems with large inter-electron interaction strength in synthesized structures. Both,
(i) the Fermi-liquids in 2D and quasi-2D systems and;
(ii) quasi-1D systems (with potentially non-Fermi-liquid ground states) will be studied. In particular, quantum phase transitions of electron liquids to solids and to other non-trivial phases (such as ferromagnetic, anti-ferromagnetic, charge- and spin-density wave, electron paired superconducting states) will be sought for and studied. In the studies, the effect of the e-e interaction will be tuned in three different ways: by "chemical doping" and intercalation, by pressure tuning the dimensionality, and by electrical tuning the carrier density (and thus the interaction strength) in the surface layer.

In total, the project will answer the question on the existence and on the physical properties of new quantum phases and quantum phase transitions in electron systems of reduced dimensionality with extremely strong interaction strength. The results obtained will be of fundamental importance for the emerging fields of organic superconductors, electrically tuned superconductors and for single-electron devices based on individual organic molecules.

Convocatoria de propuestas

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Régimen de financiación

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Coordinador

Johannes Kepler University of Linz
Aportación de la UE
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Dirección
Altenbergerstrasse 69
4040 Linz
Austria

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Coste total
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Participantes (7)