Density-functional description of superconducting and magnetic proximity effects across a tunneling barrier

TL;DR

This paper develops a density-functional formalism that unifies descriptions of superconductivity and magnetism, and applies it to analyze proximity effects across a tunneling barrier, deriving exact relations for eigenstates and eigenvalues.

Contribution

It introduces a unified density-functional approach for superconducting and magnetic proximity effects, including a novel relation connecting eigenstates across a tunneling barrier.

Findings

Derived an exact expression relating eigenstates across the barrier.

Unified Kohn-Sham equations for superconductors and non-collinear magnetism.

Applied formalism to coupled quantum liquids with tunneling.

Abstract

A density-functional formalism for superconductivity {\em and} magnetism is presented. The resulting relations unify previously derived Kohn-Sham equations for superconductors and for non-collinear magnetism. The formalism, which discriminates Cooper pair singlets from triplets, is applied to two quantum liquids coupled by tunneling through a barrier. An exact expression is derived, relating the eigenstates and eigenvalues of the Kohn-Sham equations, unperturbed by tunneling, on one side of the barrier to the proximity-induced ordering potential on the other.