Organic superconductivity: an experiment based theory

Abstract

Within the last decade the superconducting critical temperature in the organics has gone up from about 1K to greater than 10K, but the search for a comprehensive theory is still on. A completely experiment based theory is presented here. The only special features of the organic superconductors, as compared to other segregated stack charge-transfer solids, are quasi-two dimensionality (as opposed to the more common one dimensionality) and quarter-filled bands. We have shown earlier that there exists a single theoretical model which explains the experimental behavior of the complete family of one dimensional charge transfer solids, including enhanced as well as unenhanced magnetic susceptibility, occurrence as well as nonoccurrence of 4k_F instability, -the actual behavior depending on the bandfilling. It will now be shown that the same theoretical model, when extended to two dimension, explains organic superconductivity. Structural distortion driven by Coulomb repulsion, and not magnetism, is the key to understanding exotic non-BCS superconductivity. Numerical results supporting the present model are presented.