Strongly spin-polarized current generated in Zeeman-split unconventional superconductors

TL;DR

This paper demonstrates that in thin-film normal metal/superconductor junctions with p-wave symmetry, a strongly spin-polarized current can be generated due to the interplay of surface states, order parameter symmetry, and Zeeman splitting, offering a new way to produce fully spin-polarized currents.

Contribution

It reveals a novel mechanism for generating fully spin-polarized currents in p-wave superconductors involving zero-energy surface states and Zeeman splitting.

Findings

Strong spin polarization in p-wave superconductors due to surface states.

Dependence of polarization on the orbital symmetry of the superconductor.

Zero-energy surface states are crucial for fully spin-polarized current generation.

Abstract

We consider a thin-film normal metal/superconductor junction in the presence of an externally applied in-plane magnetic field for several symmetries of the superconducting order parameter. For p-wave superconductors, a strongly spin-polarized current emerges due to an interplay between the nodal structure of the superconducting order parameter, the existence or non-existence of zero-energy surface states, and the Zeeman-splitting of the bands which form superconductivity. Thus, the polarization depends strongly on the orbital symmetry of the superconducting state. Our findings suggest a mechanism for obtaining fully spin-polarized currents crucially involving zero-energy surface states, not present in s-wave superconductors.