A microscopic model of current-induced switching of magnetization

The behaviour of the magnetization in a ferromagnetic metal/nonmagnetic insulator/ferromagnetic metal/paramagnetic metal tunnel junction is studied, using the nonequilibrium Keldysh formalism. The two ferromagnets are described using the single-band Hubbard model. The left one is treated in the mean field approximation and the right ferromagnet within a (nonequilibrium) spectral density approach which takes interactions beyond the mean field into account. When a voltage is applied to the junction we observe a change of the relative orientation of the two magnetizations, which can be switched from parallel to antiparallel alignment and vice versa. This switching appears in a self-consistent way, so there is no need to use half-classical methods like the Landau-Lifshitz-Gilbert equation one. The dependence of the critical voltage at which the magnetization changes its sign on the model parameters can be studied in a systematic way.