Attractive Hubbard model: Homogeneous Ginzburg–Landau expansion and disorder


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We derive a Ginzburg–Landau (GL) expansion in the disordered attractive Hubbard model within the combined Nozieres–Schmitt-Rink and DMFT+Σ approximation. Restricting ourselves to the homogeneous expansion, we analyze the disorder dependence of GL expansion coefficients for a wide range of attractive potentials U, from the weak BCS coupling region to the strong-coupling limit, where superconductivity is described by Bose–Einstein condensation (BEC) of preformed Cooper pairs. We show that for the a semielliptic “bare” density of states of the conduction band, the disorder influence on the GL coefficients A and B before quadratic and quartic terms of the order parameter, as well as on the specific heat discontinuity at the superconducting transition, is of a universal nature at any strength of the attractive interaction and is related only to the general widening of the conduction band by disorder. In general, disorder growth increases the values of the coefficients A and B, leading either to a suppression of the specific heat discontinuity (in the weak-coupling limit), or to its significant growth (in the strong-coupling region). However, this behavior actually confirms the validity of the generalized Anderson theorem, because the disorder dependence of the superconducting transition temperature Tc, is also controlled only by disorder widening of the conduction band (density of states).

作者简介

E. Kuchinskii

Institute for Electrophysics, Ural Branch

编辑信件的主要联系方式.
Email: kuchinsk@iep.uran.ru
俄罗斯联邦, Yekaterinburg, 620016

N. Kuleeva

Institute for Electrophysics, Ural Branch

Email: kuchinsk@iep.uran.ru
俄罗斯联邦, Yekaterinburg, 620016

M. Sadovskii

Institute for Electrophysics, Ural Branch; Mikheev Institute for Metal Physics, Ural Branch

Email: kuchinsk@iep.uran.ru
俄罗斯联邦, Yekaterinburg, 620016; Yekaterinburg, 620290

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