By: Peng-Bin He
At: Complexo Interdisciplinar, Anfiteatro
There are two kinds of dynamics in magnetic multi-layers. One is the spin-polarized transport, the other is the movement of local magnetic moment. The effect of magnetization configuration on transport results in the famous giant magneto-resistance (GMR). On the contrary, spin-polarized current also influence the magnetization dynamics, for example, magnetization reversal, precession, etc., which have potential applications on information process and microwave emitting.
In general, the magnetization dynamics is controlled by current and magnetic field. Here, a theoretical study is presented on the current-driven magnetic dynamics in the tilted-polarizer magnetic tri-layers without field. Utilizing stability analysis, the phase diagrams is obtained in the plane defined by the current density and the direction of pinned-layer magnetization. With the pinned-layer magnetization oriented in a certain range, one can realize different magnetic states, such as quasi-parallel and quasi-anti-parallel stable states, in-plane and out-of-plane precessions, and out-of-plane stable states by varying the current. It is found that the free-layer magnetization prefers reversal for small deviation of the fixed-layer magnetization from the film plane, while precession for big deviation. In addition, the current-driven ferromagnetic resonance in this tri-layer will be discussed.