Odd-parity Magnetism Driven by Antiferromagnetic Exchange

TL;DR

This paper introduces a group-theory-based framework to induce odd-parity spin splitting in antiferromagnetic materials without spin-orbit coupling, revealing new symmetry-breaking states with potential spintronics applications.

Contribution

It develops a microscopic theory for odd-parity spin splitting in coplanar AFM states, identifying new ground states and symmetry-breaking orders without relying on spin-orbit coupling.

Findings

Large odd-parity spin-splitting energy scale.

Scalar odd-parity order induces non-zero Berry curvature dipole.

Identification of 67 candidate materials in the Magndata database.

Abstract

Realizing odd-parity, time-reversal-preserving, non-relativistic spin splitting is a central goal for spintronics applications. We propose a group-theory-based microscopic framework to induce odd-parity spin splitting from coplanar antiferromagnetic (AFM) states without spin-orbit coupling (SOC). We develop phenomenological models for 421 conventional period-doubling AFM systems in non-symmorphic space groups and construct minimal microscopic models for 119 of these. We find that these AFM states can attain three possible competing ground states. These ground states all break symmetries in addition to those broken by the usual AFM order. Specifically, they give rise to either odd-parity spin-splitting, nematic order, or scalar odd-parity order related to multiferroicity. Our microscopic theories reveal that the odd-parity spin-splitting energy scale is generically large and further reveal that the scalar odd-parity order gives a non-zero Berry curvature dipole without SOC. We identify 67 materials in the Magndata database for which our theory applies. We provide DFT calculations on FeSe that reveal an $h$-wave spin splitting consistent with our symmetry arguments and apply our microscopic model to determine the non-relativistic Edelstein response for CeNiAsO.