Highly efficient and tuneable spin-to-charge conversion through Rashba coupling at oxide interfaces

TL;DR

This paper demonstrates highly efficient, tunable spin-to-charge conversion at oxide interfaces using Rashba spin-orbit coupling in LaAlO3/SrTiO3, surpassing bulk limitations and enabling gate-controlled spintronics functionalities.

Contribution

It introduces an interface-driven Rashba effect in oxide 2DES for efficient, tunable spin-charge conversion, surpassing traditional bulk spin Hall efficiencies.

Findings

Achieved unprecedented spin-to-charge conversion efficiency.

Demonstrated strong gate voltage modulation of the effect.

Linked the effect's amplitude to the electronic structure of the 2DES.

Abstract

The spin-orbit interaction couples the electrons' motion to their spin. Accordingly, passing a current in a material with strong spin-orbit coupling generates a transverse spin current (spin Hall effect, SHE) and vice-versa (inverse spin Hall effect, ISHE). The emergence of SHE and ISHE as charge-to-spin interconversion mechanisms offers a variety of novel spintronics functionalities and devices, some of which do not require any ferromagnetic material. However, the interconversion efficiency of SHE and ISHE (spin Hall angle) is a bulk property that rarely exceeds ten percent, and does not take advantage of interfacial and low-dimensional effects otherwise ubiquitous in spintronics hetero- and mesostructures. Here, we make use of an interface-driven spin-orbit coupling mechanism - the Rashba effect - in the oxide two-dimensional electron system (2DES) LaAlO3/SrTiO3 to achieve spin-to-charge conversion with unprecedented efficiency. Through spin-pumping, we inject a spin current from a NiFe film into the oxide 2DES and detect the resulting charge current, which can be strongly modulated by a gate voltage. We discuss the amplitude of the effect and its gate dependence on the basis of the electronic structure of the 2DES.