Tunable Rashba spin-orbit interaction at oxide interfaces

TL;DR

This paper demonstrates that the Rashba spin-orbit interaction at LaAlO3/SrTiO3 interfaces can be significantly tuned by external electric fields, with a sharp increase near the quantum critical point between insulating and superconducting phases.

Contribution

It provides the first detailed experimental investigation of electric-field tunable Rashba spin-orbit coupling at oxide interfaces, revealing its critical behavior near phase transitions.

Findings

Rashba interaction magnitude can be modulated by electric fields.

A steep increase in Rashba coupling occurs near the quantum critical point.

Spin-orbit coupling evolution correlates with phase diagram features.

Abstract

The quasi-two-dimensional electron gas found at the LaAlO3/SrTiO3 interface offers exciting new functionalities, such as tunable superconductivity, and has been proposed as a new nanoelectronics fabrication platform. Here we lay out a new example of an electronic property arising from the interfacial breaking of inversion symmetry, namely a large Rashba spin-orbit interaction, whose magnitude can be modulated by the application of an external electric field. By means of magnetotransport experiments we explore the evolution of the spin-orbit coupling across the phase diagram of the system. We uncover a steep rise in Rashba interaction occurring around the doping level where a quantum critical point separates the insulating and superconducting ground states of the system.