Andreev reflection between a normal metal and the FFLO superconductor II: a self-consistent approach

TL;DR

This paper presents a self-consistent theoretical study of Andreev reflection at a normal metal–FFLO superconductor interface, revealing a magnetic-field-dependent conductance peak called the Andreev window, differing from previous non-self-consistent models.

Contribution

It introduces a self-consistent mean-field approach to analyze Andreev reflection in FFLO superconductors, accounting for key parameters like the gap and pair momentum.

Findings

Identification of the Andreev window near the upper critical field

Conductance peaks depend on barrier strength and magnetic field

Self-consistent calculations differ from previous models

Abstract

We consider Andreev reflection in a two dimensional junction between a normal metal and a heavy fermion superconductor in the Fulde-Ferrell (FF) type of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. We assume s-wave symmetry of the superconducting gap. The parameters of the superconductor: the gap magnitude, the chemical potential, and the Cooper pair center-of-mass momentum Q, are all determined self-consistently within a mean-field (BCS) scheme. The Cooper pair momentum Q is chosen as perpendicular to the junction interface. We calculate the junction conductance for a series of barrier strengths. In the case of incoming electron with spin \sigma = 1 only for magnetic fields close to the upper critical field H_{c2}, we obtain the so-called Andreev window i.e. the energy interval in which the reflection probability is maximal, which in turn is indicated by a peak in the conductance. The last result differs with other non-self-consistent calculations existing in the literature.