Probing Fermi-surface spin-textures via the nonlinear Shubnikov-de Haas effect

TL;DR

This paper introduces the nonlinear Shubnikov-de Haas effect as a sensitive method to probe spin-orbit interactions and spin textures in materials, enabling differentiation between types of Rashba couplings.

Contribution

It demonstrates that the nonlinear SdH effect can distinguish different spin-orbit coupling types, providing a new tool for material characterization in spintronics and quantum technologies.

Findings

NSdH effect is highly sensitive to spin textures from SOI

NSdH oscillation phase and beating distinguish SOI types

Can differentiate linear and cubic Rashba couplings in germanium

Abstract

The coupling of spin and electronic degrees of freedom via the spin-orbit interaction (SOI) is an essential ingredient for many proposed future technologies. However, probing the strength and nature of SOI is a significant challenge, especially in heterostructures. Here, we consider the nonlinear Shubnikov-de Haas (NSdH) effect, a quantum oscillatory effect that occurs under conditions similar to those of the well-known SdH effect, but is second order in the applied electric field. We demonstrate that, unlike its linear counterpart, the NSdH effect is highly sensitive to the spin textures that arise from SOI. In particular, we show that the phase and beating of NSdH oscillations in nonlinear conductivities can clearly distinguish between different types of SOI. As a demonstration, we show how NSdH can distinguish between the linear and cubic Rashba couplings that are expected in germanium heterostructures. Our results establish the NSdH effect as a powerful and sensitive probe of SOI, offering a new framework for characterizing materials relevant to topology, spintronics, and solid-state quantum information technologies.