Mesoscopic competition of superconductivity and ferromagnetism: conductance peak statistics in metallic grains

TL;DR

This paper explores how superconductivity and ferromagnetism coexist in tiny metallic grains, analyzing their effects on conductance fluctuations to understand the interplay of these competing phases.

Contribution

It introduces an effective Hamiltonian combining BCS pairing and Stoner exchange to study mesoscopic conductance fluctuations in coexisting superconducting and ferromagnetic states.

Findings

Signatures of coexistence observed in conductance peak statistics

Mesoscopic fluctuations reveal interplay between pairing and exchange

Transport properties affected by competition between phases

Abstract

We investigate the competition between superconductivity and ferromagnetism in chaotic ultra-small metallic grains in a regime where both phases can coexist. We use an effective Hamiltonian that combines a BCS-like pairing term and a ferromagnetic Stoner-like spin exchange term. We study the transport properties of the grain in the Coulomb blockade regime and identify signatures of the coexistence between pairing and exchange correlations in the mesoscopic fluctuations of the conductance peak spacings and peak heights.