Spin polarization control by electric means: proposal for a spin diode

TL;DR

This paper proposes a quantum wire-based spin diode that generates and controls large spin-polarized currents using electric fields, with potential for robust spintronic applications.

Contribution

It introduces a novel spin diode design utilizing Rashba spin-orbit interaction and asymmetric quantum wires, enabling electric control of spin currents with high robustness.

Findings

Large spin-polarized current when electrons flow from narrow to wide lead

Spin polarization vanishes or weakens in reverse direction

Device demonstrates robustness against disorder

Abstract

A scheme of spin diode is proposed that uses a step-like quantum wire with Rashba spin-orbit interaction, connected to two leads with different width. It is shown that a very large vertical spin-polarized current can be generated when electrons transmit from the narrow lead to the wide lead, however, it vanishes or becomes very weak when the transport direction is reversed. This difference is revealed to arise from the different local density of electron states of the quantum wire, which is dependent on the direction of bias. The spin-polarized current in the proposed structure can be generated and manipulated by purely electric means and with strong a robustness against disorder, displaying the feasibility of this structure for a real application.