Tunneling spin current and spin diode behavior in bilayer system

TL;DR

This paper investigates the tunneling spin current in bilayer systems with spin-orbit coupling, revealing how wavefunction overlaps and impurities influence spin transport and diode-like behavior.

Contribution

It introduces a new definition of tunneling spin current based on wavefunction overlaps and analyzes impurity effects on spin conductivity in bilayer systems.

Findings

Tunneling spin current depends on wavefunction overlaps between layers.

Impurity potentials cause asymmetry in spin conductivity relative to gate voltage.

The system exhibits spin diode behavior influenced by impurity strength differences.

Abstract

The coherent tunneling spin current in the bilayer system with spin-orbit coupling is investigated. Based on the continuity-like equations, we discuss the definition of the tunneling current and show that the overlaps between wavefunctions for different layers contribute to the tunneling current. We study the linear response of the tunneling spin current to an in-plane electric field in the presence of nonmagnetic impurities. The tunneling spin conductivity we obtained presents a feature asymmetrical with respect to the gate voltage when the strengthes of impurity potentials are different in each layer.