Time Reversal Symmetry Breaking and Spontaneous Currents in s-Wave / Normal Metal / d-Wave Superconductor Sandwiches

TL;DR

This paper investigates how phase-dependent Andreev bound states in an s-wave/normal metal/d-wave superconductor junction can lead to broken time reversal symmetry and spontaneous supercurrents, using Ginzburg-Landau and Bogolyubov-de Gennes theories.

Contribution

It demonstrates the emergence of time reversal symmetry breaking and spontaneous currents in such junctions based on phase-dependent bound states and theoretical analysis.

Findings

Broken time reversal symmetry occurs for generic orientations.

Spontaneous supercurrents are generated along the junction.

The phenomena are explained via Ginzburg-Landau and Bogolyubov-de Gennes models.

Abstract

We study the physical properties of an $s$-wave -- normal metal -- $d$-wave junction in terms of the Andreev bound states in the normal metal layer. The phase dependence of bound states with different orientations leads to superconducting states with broken time reversal symmetry for generic orientations of the $d$-wave superconductor crystal. The occurrence of such a state and the associated spontaneous supercurrent along the junction is analyzed in the framework of Ginzburg-Landau theory and by the solution of the Bogolyubov-de Gennes equations.