Microscopic mechanism for C-60 superconductivity
Hoboken :John wiley & sons inc
International journal of quantum chemistry. - New York, N.Y.
42nd Annual Sanibel Symposium, FEB 23-MAR 01, 2002, ST AUGUSTINE, FLORIDA
, p. 261-275
After a brief discussion of the four classes of superconducting materials, attention is focused on the fullerides. More critically, motivated by the work of Herzberg and Longuet-Higgins (HLH), especially in the context of the Berry phase, and the topological superconducting model of Wiegmann we propose a microscopic model of C-60 superconductivity. One key is the relationship of the HLH phase sign change of the wave function circling a degeneracy. The sign change is related to a topological quantity, a Chern number, which is a requirement specified for a topological superconductor, following Weigmann. Thus, it seems vibrational modes are topologically and coherently coupled to the electronic wave function. We establish a microscopic basis, for topological superconductivity using Weigmann's generalization of Frohlich's 1-D model to two dimensions. This necessarily invokes the nonlinear sigma model and the addition of topological terms. We then reinterpret the work of Auerbach et al. and O'Brien by suggesting that vibrational analysis of C-60 with Jahn-Teller distortions that produce a collective mode(s) that could be described by a soliton or, equivalently, a skyrmion model. The soliton (skyrmion) statistics are such that both fermions and bosons result depending on the number of electrons, n. Superconductivity is predicted for n = 3, and possibly 5 electrons, and n = 2 and 4 should be insulators. The strong coupling theory developed seems appropriate for describing a molecular superconductor. (C) 2003 Wiley Periodicals, Inc.