Measurement of Rashba and Dresselhaus spin-orbit magnetic fields

TL;DR

This paper presents a universal optical method to measure and distinguish Rashba and Dresselhaus spin-orbit magnetic fields in semiconductors, enabling better characterization for spintronic device development.

Contribution

It introduces a novel optical technique to quantify both Rashba and Dresselhaus spin-orbit fields simultaneously in a single sample.

Findings

Both spin-orbit fields can be measured via spin precession angular dependence.

Spin resonance can be induced by the spin-orbit fields.

Method applied to GaAs/InGaAs quantum wells, applicable to other semiconductors.

Abstract

Spin-orbit coupling is a manifestation of special relativity. In the reference frame of a moving electron, electric fields transform into magnetic fields, which interact with the electron spin and lift the degeneracy of spin-up and spin-down states. In solid-state systems, the resulting spin-orbit fields are referred to as Dresselhaus or Rashba fields, depending on whether the electric fields originate from bulk or structure inversion asymmetry, respectively. Yet, it remains a challenge to determine the absolute value of both contributions in a single sample. Here we show that both fields can be measured by optically monitoring the angular dependence of the electrons' spin precession on their direction of movement with respect to the crystal lattice. Furthermore, we demonstrate spin resonance induced by the spin-orbit fields. We apply our method to GaAs/InGaAs quantum-well electrons, but it can be used universally to characterise spin-orbit interactions in semiconductors, facilitating the design of spintronic devices.