Large Surface Magnetization in Noncentrosymmetric Antiferromagnets

TL;DR

This paper predicts a large surface magnetization in thin-film antiferromagnets with Rashba spin-orbit coupling, enabling new methods for probing and controlling antiferromagnetic spin dynamics.

Contribution

It introduces the concept that Dzyaloshinskii-Moriya interaction induces significant surface magnetization and boundary twist states in antiferromagnets, with potential for ultrafast terahertz applications.

Findings

Magnetization of about 2.3×10^4 A/m predicted in AFs.

Surface magnetization exhibits ultrafast terahertz dynamics.

No stray magnetic fields except at corners with magnetic monopoles.

Abstract

Thin-film antiferromagnets (AFs) with Rashba spin-orbit coupling are theoretically investigated. We demonstrate that the relativistic Dzyaloshinskii-Moriya interaction (DMI) produces a large surface magnetization and a boundary-driven twist state in the antiferromagnetic N\' eel vector. We predict a magnetization on the order of $2.3\cdot 10^4$~A/m, which is comparable to the magnetization of ferromagnetic semiconductors. Importantly, the magnetization is characterized by ultra-fast terahertz dynamics and provides new approaches for efficiently probing and controlling the spin dynamics of AFs as well as detecting the antiferromagnetic DMI. Notably, the magnetization does not lead to any stray magnetic fields except at corners where weak magnetic monopole fields appear.