Nonlocal pure spin current injection via quantum pumping and crossed Andreev reflection

TL;DR

This paper proposes a device that uses adiabatic quantum pumping and crossed Andreev reflection in a ferromagnet-superconductor-semiconductor system to generate a nonlocal pure spin current, with potential experimental implementation.

Contribution

It introduces a novel method for pure spin current injection leveraging quantum pumping and crossed Andreev reflection in a three-terminal device.

Findings

Pure spin current can be nonlocally injected via adiabatic modulation.

Crossed Andreev reflection enhances nonlocal spin injection.

Theoretical analysis suggests feasible experimental realization.

Abstract

A pure spin current injector is proposed based on adiabatic pumping and crossed normal/Andreev reflection. The device consists of a three-terminal ferromagnet-superconductor-semiconductor system in which the injection of a pure spin current is into the semiconductor which is coupled to the superconductor within a coherence length away from the ferromagnet enabling the phenomena of crossed normal /Andreev reflection to operate. Quantum pumping is induced by adiabatically modulating two independent parameters of the ferromagnetic lead, namely the magnetization strength and the strength of coupling between the ferromagnet and the superconductor. The competition between the normal/Andreev reflection and the crossed normal/Andreev reflection, both induced by pumping, leads to non-local injection of a pure spin current into the semiconductor. The experimental realization of the proposed device is also discussed.