Strain-Tunable Anomalous Hall Plateau in Antiferromagnet CoNb ₃ S ₆

Antiferromagnets with anomalous Hall effects offer a compelling link among magnetism, topology, and electronic structure. Identifying antiferromagnets with large and tunable anomalous Hall effects is crucial for the development of spintronic applications. We report a strain-tunable anomalous Hall plateau in CoNb₃S₆, a layered antiferromagnet known for its unexpectedly large anomalous Hall conductivity. The plateau emerges as a flat, extended intermediate step in the Hall hysteresis loop with the step height tunable by temperature and strain. Unlike typical magnetic plateaus tied to metastable states, this behavior suggests a hidden phase transition that alters magnetic anisotropy without changing the magnetic order. Symmetry analysis suggests that the hidden phase preserves the rotational symmetry of the <i>ab</i> plane. The plateau reflects phase coexistence during the hidden transition and exhibits non-volatile anomalous Hall resistivity, enabling a novel four-state Hall switching.