Linear and Nonlinear Edelstein Effects in Chiral Topological Semimetals

TL;DR

This paper predicts the linear and nonlinear Edelstein effects in chiral topological semimetal CoSi, showing how electric and optical fields can control magnetization, with implications for spintronics and magnetic memory devices.

Contribution

First-principles predictions of both linear and nonlinear Edelstein effects in CoSi, revealing their dependence on symmetry and potential for magnetic control.

Findings

Both effects require time-reversal symmetry breaking.

Opposite and identical signs of effects in CoSi enantiomers.

Magnetization can reach 10 Bohr magnetons per unit cell.

Abstract

Recently, there has been growing interest in achieving on-demand control of magnetism through electrical and optical means. In this work, we provide first-principles predictions for the linear and nonlinear Edelstein effects (LEE and NLEE) in the chiral topological semimetal CoSi. The LEE and NLEE represent first- and second-order magnetic responses to external electric fields, enabling precise manipulation of magnetization via electrical and optical methods. We demonstrate that although both LEE and NLEE require time-reversal symmetry breaking, they can still be realized in non-magnetic materials, as time-reversal symmetry can be spontaneously broken by heat and dissipation, according to the second law of thermodynamics. Meanwhile, due to different inversion symmetry selection rules, the LEE and NLEE manifest opposite and identical signs in the two enantiomers of CoSi, respectively. We further quantify the magnitude of LEE and NLEE, showing that electrically or optically induced magnetization can reach 10 Bohr magneton per unit cell when the external electric field strength is comparable with the internal atomic electric field, which is on the order of 1 V/A. Our work offers a systematical approach for predicting the electrical and optical control of magnetism in real materials, paving the way for potential applications in areas such as spintronics and magnetic memories.