Evidence of linear and cubic Rashba effect in non-magnetic heterostructure

TL;DR

This study uses first-principles calculations to reveal the presence of linear and cubic Rashba effects in LaAlO3/KTaO3 heterostructures, highlighting their potential for spintronic and optoelectronic applications.

Contribution

It provides the first detailed analysis of Rashba interactions in defect-free LaAlO3/KTaO3 interfaces, distinguishing between Type-I and Type-II heterostructures.

Findings

Type-I heterostructure exhibits cubic and linear Rashba effects.

Type-II heterostructure shows spin-splitting with only linear Rashba.

Type-II interface enables potential photocurrent transition for photogalvanic studies.

Abstract

The LaAlO3/KTaO3 system serves as a prototype to study the electronic properties that emerge as a result of spin-orbit coupling. In this article, we have used first-principles calculations to systematically study two types of defect-free (0 0 1) interfaces, which are termed as Type-I and Type-II. While the Type-I heterostructure produces a two-dimensional electron gas, the Type-II heterostructure hosts an oxygen-rich two-dimensional hole gas at the interface. Furthermore, in the presence of intrinsic spin-orbit coupling, we have found evidence of both cubic and linear Rashba interactions in the conduction bands of the Type-I heterostructure. On the contrary, there is spin-splitting of both the valence and the conduction bands in the Type-II interface, which are found to be only linear Rashba type. Interestingly, the Type-II interface also harbours a potential photocurrent transition path, making it an excellent platform to study the circularly polarized photogalvanic effect.