From spin diffusion to magnetization reversal : the four channel approach

摘要

Experiments of spin injection, from a normal metal to a ferromagnet, show that the magnetization of theferromagnet can be switched with high current pulses, without the need of a magnetic field. In order to describethe experimental observations, two different kinds of electronic populations are defined for the transport: the spinpolarized current inside the normal metal (paramagnetic spin-polarized current) and the spin-polarized currentinside the ferromagnet (ferromagnetic spin polarization). The redistribution of the electronic populations isthen investigated in the framework of a four-channel approach (up and down spin polarization for paramagneticand ferromagnetic currents) . This mechanism couples the electronic transport (Boltzmann equations) to thedynamics of the magnetization (Landau-Lifshitz-Gilbert equation), and leads to define a magnetic temperaturewhich depends on the current injection.