Generating Giant Spin Currents Using Nodal Topological Superconductors

TL;DR

This paper demonstrates that giant spin currents can be generated in nodal topological superconductors via Majorana fermions, leveraging selective equal spin Andreev reflections, with implications for spintronics.

Contribution

It introduces a novel mechanism for generating large spin currents in nodal topological superconductors using Majorana fermions and SESAR.

Findings

Giant spin current can be injected using Majorana fermions.

Edge pairing correlation is predominantly equal spin-triplet at zero energy.

SESAR causes injection of spin-polarized electron pairs.

Abstract

In this work, we show that a giant spin current can be injected into a nodal topological superconductor, using a normal paramagnetic lead, through a large number of zero energy Majorana fermions at the superconductor edge. The giant spin current is caused by the selective equal spin Andreev reflections (SESAR) induced by Majorana fermions. In each SESAR event, a pair of electrons with certain spin polarization are injected into the nodal topological superconductor, even though the pairing in the bulk of the nodal superconductor is spin-singlet s-wave. We further explain the origin of the spin current by showing that the pairing correlation at the edge of a nodal topological superconductor is predominantly equal spin-triplet at zero energy. The experimental consequences of SESAR in nodal topological superconductors are discussed.