Multi-rotational switching in a noncollinear antiferromagnet by spin-orbit torque
Spintronics has advanced through discoveries of various electrically-driven spin dynamics in nanomagnets. Here, we report a novel switching dynamics of spin systems driven by spin-orbit torque, using a noncollinear antiferromagnetic nanodot. With electric pulses spanning a wide range of durations and amplitudes, we find an unconventional insensitivity of a threshold current density to pulse duration in switch-back events. This observation is attributed to a previously unrecognized process, in which the noncollinear antiferromagnetic order undergoes multiple rotations before completing reversal, a phenomenon we term multi-rotational switching. Our theoretical analysis reveals that multi-rotational switching arises from the interplay of three key factors: current-driven coherent rotation of the noncollinear antiferromagnetic order, field-induced reorientation of the uncompensated net magnetization, and thermal fluctuations. These findings establish a microscopic mechanism governing current-induced switching in noncollinear antiferromagnets, a topic of growing interest for next-generation spintronics technologies, opening a new route to controlling antiferromagnetic order in nanodevices.