Spin-orbit interaction based spintronics

Abstract

Spin-orbit interaction (SOI) is a relativistic effect and produces a momentum dependent effective magnetic field when electron spins travel in an electric field. The spin angular momentum and orbital motion of electrons are coupled by SOI, e.g., leading to the spin Hall effect, where spin-up and -down electrons are deflected into opposite directions. By exploiting these unique features, we can create spin functionalities in SOI systems without using an external magnetic field. SOI based spintronics is often called “spin-orbitronics”. This chapter focuses on Rashba and Dresselhaus SOIs and their applications for spintronics in semiconductor heterostructures. Especially Rashba SOI is rather interesting since the strength is controlled by the gate voltage on top of the semiconductor's two-dimensional electron and hole gases. By utilizing the effective magnetic field induced by the Rashba SOI, spin generation, manipulation, and detection are possible by electrostatic ways. However, the drawback of SOI is to give rise to spin relaxation because of the momentum dependent magnetic field. Long spin coherence is achieved by special spin helix state where both Rashba and Dresselhaus SOIs are equal.