A magnetic fluctuation state driven by a mesoscopic spin transfer torque

A current-induced magnetic fluctuation state in mesoscopic systems such as a dilute magnetic semiconductors is theoretically predicted. We investigate coherent electron transport and the dynamics of the local magnetic moment of a ferromagnetic nano-pillar system where the current-induced magnetization switching is realized in macroscopic samples. The exchange coupling between the spins of the conduction electrons and the local spins is taking into account by using the numerical technique. An interference related non-uniform spin-polarized current causes a non-uniform spin transfer torque. We show that this mesoscopic spin torque generates a spatio-temporal magnetic fluctuation state in the local spin system. We propose the measurement of the time dependent conductance fluctuation for observing the magnetic fluctuation state