Electric Field Tuning of the Rashba Effect in the Polar Perovskite Structures

TL;DR

This paper demonstrates how applying an electric field can tune the Rashba effect at polar perovskite surfaces and interfaces by controlling the 2DEG distribution, supported by density-functional and tight-binding analyses.

Contribution

It introduces a method to electrically control the Rashba effect in polar perovskites, providing a theoretical framework for understanding experimental observations.

Findings

Electric field modulates the 2DEG position at the surface.

Density-functional calculations confirm tunability of the Rashba effect.

Tight-binding model explains the interplay of spin-orbit coupling and surface asymmetry.

Abstract

We show that the Rashba effect at the polar perovskite surfaces and interfaces can be tuned by manipulating the two-dimensional electron gas (2DEG) by an applied electric field, using it to draw the 2DEG out to the surface or push it deeper into the bulk, thereby controlling the surface-sensitive phenomenon. These ideas are illustrated by a comprehensive density-functional study of the recently-discovered polar KTaO$_3$ surface. Analytical results obtained with a tight-binding model unravel the interplay between the various factors affecting the Rashba effect such as the strength of the spin-orbit interaction and the surface-induced asymmetry. Our work helps interpret the recent experiments on the KTaO$_3$ surface as well as the SrTiO$_3$/LaAlO$_3$ interface.