Spin current injection by intersubband transitions in quantum wells

TL;DR

This paper demonstrates that linearly polarized infrared light can induce pure spin currents in quantum wells through intersubband transitions, with controllable magnitude and direction via spin-orbit coupling and external bias.

Contribution

It introduces a method to generate and manipulate pure spin currents in quantum wells using optical excitation and external bias, highlighting potential for spintronic applications.

Findings

Spin current can be injected by infrared radiation in quantum wells.

The spin current's magnitude and direction depend on spin-orbit coupling and light frequency.

Injected spin currents are detectable via spin-Hall effect or optical spectroscopy.

Abstract

We show that a pure spin current can be injected in quantum wells by the absorption of linearly polarized infrared radiation, leading to transitions between subbands. The magnitude and the direction of the spin current depend on the Dresselhaus and Rashba spin-orbit coupling constants and light frequency and, therefore, can be manipulated by changing the light frequency and/or applying an external bias across the quantum well. The injected spin current should be observable either as a voltage generated via the anomalous spin-Hall effect, or by spatially resolved pump-probe optical spectroscopy.