Spin-Transfer in Magnetic Tunnel Junctions with Resonance Sates due to Impurities

One of the main difficulties in designing the effectively working magnetic cell is the fact that the amplitude of the current-driven torque acting on the magnetization of the free layer in a single-barrier MTJ is usually too small. To overcome this difficulty, we suggest introducing magnetic impurities inside the barrier in order to create resonance electron states inside it. We consider an MTJ with non-collinear magnetizations of the ferromagnetic electrodes and we use the s-d exchange model and non-equilibrium Keldysh technique to calculate spin-polarized current and non-equilibrium magnetization of itinerant s electrons tunneling through the barrier.The position of the resonance depends on the electron energy, the impurity potential and the position of this impurity inside the barrier and bias voltage, so numerical calculations were performed to investigate torque in different tunneling regimes.