Crystallographic Spin‐Orbit Torque From Epitaxial CrSb

Abstract

Altermagnets (AMs) represent an emerging magnetic phase that combines compensated antiferromagnetic order with ferromagnet‐like spin‐splitting, offering a new route for efficient spin‐current generation. Here, we experimentally demonstrate spin‐torque generation in epitaxial CrSb and reveal a pronounced crystallographic dependence of the resulting spin‐orbit torques (SOTs) across the ( 11¯00$1\overline{1}00$ ) and ( 112¯0$11\overline{2}0$ ) orientations. Using spin‐torque ferromagnetic resonance, we identify unconventional SOT behavior, including a finite x‐polarized damping‐like torque and reversal of the y‐polarized damping‐like torque between the two crystal planes, features that cannot be explained by conventional spin Hall or Rashba–Edelstein mechanisms. The damping‐like torque efficiencies are comparable to those of heavy metals and exhibit strong in‐plane anisotropy directly linked to crystal symmetry. Symmetry analysis shows that the observed angular dependence originates from a crystallographic torque permitted by the C2v point group, whereas AM‐specific contributions from the magnetic spin Hall and spin‐splitter effects remain negligible due to the multi‐domain state and weak strain‐induced g‐to‐d spin symmetry deformation in CrSb. These findings show that epitaxial CrSb can host strongly anisotropic spin‐torques governed primarily by crystallographic and interfacial symmetry, providing a route toward crystallographically engineered spintronic devices.