Uniaxial Strain Tuned Magnetism of the Altermagnet Candidate H‐FeS

Altermagnets are a newly recognized class of magnetic materials characterized by compensated spin configurations while still breaking time‐reversal symmetry and exhibiting unconventional transport phenomena. Hexagonal FeS (h‐FeS) is a recently identified altermagnet candidate that shows a spontaneous anomalous Hall effect (AHE) accompanied by a tiny net magnetization. Here, we show that both the spontaneous AHE and magnetization can be effectively suppressed by an in‐plane compressive strain. Since neutron diffraction measurements show that the applied uniaxial strain only modifies the in‐plane domain population but does not affect the in‐plane magnetic structure, the major effect of the applied strain is to tune the small ‐axis ferromagnetic moment. Our results demonstrate a strong correlation between the tiny net magnetization and the spontaneous AHE in h‐FeS, and show that uniaxial strain provides an effective knob to tune both properties in this altermagnet candidate for spintronic applications.