Magnetization Vector Control and Resistance Analysis of STT p-MTJ Devices

摘要

The resistance of perpendicular MTJ devices (p-MT J)is changed when the magnetization vector of its free ferromagnetic layer is pointed to different angles. However, the MTJ resistance depends not only on the momentary status of the angle of magnetization vector but also on the rate of its change which is determined by the LLG vector differential equation. By maximizing the rate of the changes, faster devices can be obtained. It is shown that an optimum operation point can be found. At this operation point the device switches fast while consumes fair amount of power. The approach is verified using an evaluation circuit and spice simulations. It is shown that MRAM-cell designers can find optimum values ofW/L for the CMOS-transistors to achieve better performance in the whole circuit.