Experimental and theoretical aspects of thermodynamic properties of quasi-1D and quasi-2D organic conductors and superconductors

Abstract

We deal with thermodynamic features of organic conductors and superconductors where itinerant [Formula: see text]-electrons/holes released from organic molecules are playing essential roles for electronic properties. Since they are low-dimensional electronic systems with relatively soft lattice framework, they show variety of phenomena related to electron correlations and electron–lattice coupling. The drastic changes of conductive and magnetic properties owing to quantum features of [Formula: see text]-electrons can be induced by external perturbations such as magnetic/electric field, pressure, etc. It is especially emphasized that the possible mechanism and relation with other phenomena of the superconductivity in [Formula: see text]-electrons system remains to be one of the interesting research areas in fundamental condensed matter science. In this review paper, we consider several topics of organic conductors and superconductors from the standpoints of thermodynamic experiments, data analyses and theories performed up to now. Starting from the overall picture of the electronic states in charge transfer complexes, thermodynamic properties of the quasi-one-dimensional systems, quasi-two-dimensional systems and [Formula: see text]–d interacting systems are reviewed. The thermodynamic parameters of the superconductive compounds in them are compared and discussed. The relations with crystal structures, electronic states, phase diagram and other experiments are also discussed in comparison with these thermodynamic properties. The possible pairing symmetries in organic superconductors and some models are mentioned in the last part. This review deals with a wide scope of theoretical and experimental topics in superconductivity in molecule-based conductive systems.