Néel vector rotation driven by spin–orbit torque in amorphous ferrimagnetic GdCo

Spin superfluidity, a phenomenon enabling low-dissipative spin transport, has remained a theoretical concept. To realize spin superfluidity in an antiferromagnet, it is necessary to excite a Néel vector rotation within the magnetic easy-plane, which has been elusive so far due to the large magnetocrystalline anisotropy of antiferromagnets. In this study, we demonstrated spin–orbit torque-driven Néel vector rotation in amorphous ferrimagnetic GdCo. A pseudo-magnetic easy-plane is formed in a spin-flop state under an external magnetic field in the vicinity of the magnetization compensation temperature, and we observed stochastic binary switching in the anomalous Hall resistance, directly attributed to Néel vector rotation. Furthermore, homodyne detection confirmed rotation frequencies in the GHz range as expected from atomic spin simulations, providing evidence of dynamic Néel vector behavior. These findings demonstrate the continuous rotation of Néel vector driven by spin–orbit torque.