Size-Dependent Anomalous Hall Effect In Noncollinear Antiferromagnetic Mn3sn Films

The coercive field of ferromagnets generally increases with decreasing the sample size to hundreds of nanometers mainly because of the (edge) defect pinning. We investigate size-dependent anomalous Hall effect (AHE) in (11 (2) over bar0)-oriented noncollinear antiferromagnetic Mn3Sn films. The switching field (coercive field) of the AHE decreases abruptly when the width of the Hall bar decreases to hundreds of nanometers, giving rise to the reduced coercive field from 445 to 30 mT for Hall bar with width from 2 mu m to 100nm. This observation is in contrast to the ferromagnetic counterpart. The transition from a multidomain to single domain-like mode and the reduction of Neel temperature are proposed to explain the coercivity variation. Our finding provides a promising candidate for the device miniaturization and adds a different dimension to antiferromagnetic spintronics.