Density-functional description of materials for topological qubits and superconducting spintronics

TL;DR

This paper reviews density functional theory methods for simulating complex superconducting heterostructures, focusing on magnetic and topological materials, and discusses their implications for topological qubits and superconducting spintronics.

Contribution

It introduces recent advances in the Kohn-Sham Bogoliubov-de Gennes method for material-specific simulations of superconducting heterostructures involving magnetic and topological materials.

Findings

Magnetic impurities induce Yu-Shiba-Rusinov states within the superconducting gap.

Increased impurity concentration can suppress superconductivity.

Spin-orbit coupling affects the orbital splitting of YSR states and the order parameter.

Abstract

Interfacing superconductors with magnetic or topological materials offers a playground where novel phenomena like topological superconductivity, Majorana zero modes, or superconducting spintronics are emerging. In this work, we discuss recent developments in the Kohn-Sham Bogoliubov-de Gennes method, which allows to perform material-specific simulations of complex superconducting heterostructures on the basis of density functional theory. As a model system we study magnetically-doped Pb. In our analysis we focus on the interplay of magnetism and superconductivity. This combination leads to Yu-Shiba-Rusinov (YSR) in-gap bound states at magnetic defects and the breakdown of superconductivity at larger impurity concentrations. Moreover, the influence of spin-orbit coupling and on orbital splitting of YSR states as well as the appearance of a triplet component in the order parameter is discussed. These effects can be exploited in S/F/S-type devices (S=superconductor, F=ferromagnet) in the field of superconducting spintronics.