Non-relativistic linear Edelstein effect in helical EuIn2As2

TL;DR

This paper investigates the magnetic orders in EuIn2As2, revealing a non-relativistic Edelstein effect that varies between phases, offering a way to identify the magnetic ground state.

Contribution

It provides a symmetry analysis and ab-initio calculations showing a non-relativistic Edelstein effect in EuIn2As2, distinguishing magnetic phases through spin density polarization.

Findings

Non-relativistic Edelstein effect with out-of-plane polarized spin density.

Significant contrast in Edelstein effect magnitude between helical and broken helical phases.

Identification of in-plane g-wave order exclusive to the broken helical phase.

Abstract

Motivated by the ongoing interest in understanding the actual magnetic ground state of the promising axion insulator candidate EuIn2As2, we present here a spin symmetry analysis and ab-initio calculations, aiming to identify specific exchange-dominated physics that could offer insights into the current debate. We investigate two non-collinear coplanar magnetic orders reported in this compound: the helical and broken helical phases. Our symmetry analysis shows that magnetic-exchange alone results in the formation of an out-of-plane odd-wave order in momentum space with a single un-polarized nodal plane in both phases. Additionally, we identified an in-plane g-wave order that emerges exclusively in the broken helical phase, providing a distinguishing feature for this phase. Furthermore, we report a non-relativistic Edelstein effect with a distinct out-of-plane polarized spin density that dominates over spin-orbit coupling effects. Our ab-initio calculations reveal a significant contrast in the magnitude of this effect between both phases, which could serve as a means to identify the magnetic transition and distinguish them from other magnetic ground states proposed for this compound.