Imaging orbital Rashba induced charge transport anisotropy

TL;DR

This study demonstrates how orbital textures influence charge transport anisotropy in 2D systems, specifically at LaAlO3/SrTiO3 interfaces, using combined experimental and theoretical approaches to reveal orbital Rashba effects.

Contribution

It provides the first direct experimental evidence linking orbital Rashba coupling to conductivity anisotropy in 2D quantum materials.

Findings

Orbital textures contribute to charge transport anisotropy.

Conductivity anisotropy correlates with the non-linear Hall effect.

Orbital Rashba coupling is key to understanding transport phenomena.

Abstract

Identifying orbital textures and their effects on the electronic properties of quantum materials is a critical element in developing orbitronic devices. However, orbital effects are often entangled with the spin degree of freedom, making it difficult to uniquely identify them in charge transport phenomena. Here, we present a combination of scanning superconducting quantum interference device (SQUID) current imaging, global transport measurements, and theoretical analysis, that reveals a direct contribution of orbital textures to the linear charge transport of 2D systems. Specifically, we show that in the LaAlO$_3$/SrTiO$_3$ interface, which lacks both rotation and inversion symmetries, an anisotropic orbital Rashba coupling leads to conductivity anisotropy in zero magnetic field. We experimentally demonstrate this result by locally measuring the conductivity anisotropy, and correlating its appearance to the non-linear Hall effect, showing that the two phenomena have a common origin. Our results lay the foundations for an all--electrical probing of orbital currents in two-dimensional systems.