Spin-split collinear antiferromagnets: a large-scale ab-initio study

TL;DR

This study uses large-scale ab-initio calculations to identify and analyze collinear antiferromagnets that exhibit spin-split bands due to symmetry, highlighting compounds with significant spin splitting and interesting electronic structures.

Contribution

It provides a comprehensive ab-initio analysis of spin-split bands in collinear antiferromagnets, introducing numerical measures and identifying promising compounds with notable spin-momentum textures.

Findings

Identification of compounds with large spin splitting, such as CoF2 and FeSO4F.

Discovery of materials with nearly flat spin-split bands near the Fermi energy, like LiFe2F6.

Recognition of antiferromagnetic metals with spin-split electronic structures, including RuO2, CrNb4S8, and CrSb.

Abstract

It was recently discovered that, depending on their symmetries, collinear antiferromagnets can actually break the spin degeneracy in momentum space, even in the absence of spin-orbit coupling. Such systems, recently dubbed altermagnets, are signalled by the emergence of a spin-momentum texture set mainly by the crystal and magnetic structure, relativistic effects playing a secondary role. Here we consider all collinear $q$=0 antiferromagnetic compounds in the MAGNDATA database allowing for spin-split bands. Based on density-functional calculations for the experimentally reported crystal and magnetic structures, we study more than sixty compounds and introduce numerical measures for the average momentum-space spin splitting. We highlight some compounds that are of particular interest, either due to a relatively large spin splitting, such as CoF$_2$ and FeSO$_4$F, or because of their low-energy electronic structure. The latter include LiFe$_2$F$_6$, which hosts nearly flat spin-split bands next to the Fermi energy, as well as RuO$_2$, CrNb$_4$S$_8$, and CrSb, which are spin-split antiferromagnetic metals.