Anion correlation induced nonrelativistic spin splitting in rutile antiferromagnets

The search for altermagnetic and related materials has largely focused on ideal crystals, overlooking the role of short-range chemical order. Using density functional theory and a cluster expansion model, the authors show that short-range anion correlations in iron oxyfluoride (FeOF) tune the magnitude and character of nonrelativistic spin splitting, producing splittings absent in ordered FeF${}_{2}$ and virtual-crystal approximation models. The authors further identify magneto-optical Kerr spectroscopy as a route to detect these effects experimentally and highlight heteroanionic substitution as a design strategy for high-${T}_{N}$ spin-split antiferromagnets.