Persistent spin current in mesoscopic ferrimagnetic spin ring

Using a semiclassical approach, we study the persistent magnetization current of a mesoscopic ferrimagnetic ring in a nonuniform magnetic field. At zero temperature, there exists persistent spin current because of the quantum fluctuation of magnons, similar to the case of an antiferromagnetic spin ring. At a low temperature, the current shows activation behavior because of the field-induced gap. At a higher temperature, the magnitude of the spin current is proportional to temperature T, similar to the reported result of a ferromagnetic spin ring.