Physical Considerations and Model Calculations for One-Dimensional Superconductivity
The present era of intensive research in the field of one-dimensional conductors which started with the work of the Penn group1 on TTF-TCNQ was preceded by the discussion of the possibility of superconductivity in one-dimensional organic materials which was suggested by one of us2 in 1964. In that paper a new mechanism of superconductivity was proposed. In this mechanism the effective attraction between electrons at the Fermi surface is induced by the exchange of an electronic excitation (broadly referred to as an exciton), rather than by phonons as is believed to be the case in all presently known superconductors. The main attraction of this, so called, exciton mechanism is that it apparently implies high temperature superconductivity. The one-dimensionality came in only because the system of a linear conducting spine with polarizable side chains seemed to be a suitable structure for the realization of the exciton mechanism, which requires a spatial separation between the conduction electrons and the electrons of the exciton system. We are sure that everybody would be just as happy to make the exciton mechanism work in a different geometry. Indeed, Ginzburg3 has discussed extensively the exciton mechanism in two-dimensional structures. Allender et al4 applied Ginzburg’s ideas to a specific system consisting of a thin metallic layer coated by a semiconductor with a high dielectric constant. Their work was followed by an unsuccessful attempt to find superconductivity with an enhanced transition temperature in such a system5. We believe that the one-dimensional structure still has the best prospects for a successful realization of the exciton mechanism. The reasons for this opinion will be specified in the course of this lecture.
KeywordsMomentum Dependence Vertex Correction Exciton Coupling Conducting Spine Bulky Ligand
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