Micromagnetic simulation of spin transfer torque switching by nanosecond current pulses

Magnetization reversal by spin transfer torque due to current flowing in magnetic tunnel junction nanopillar with 200 nm × 125 nm elliptical cross section is studied by micromagnetic simulation assuming the Slonczewski model for spin transfer torque. The magnetization dynamics during the switching is found to be highly inhomogeneous with formation of complex domain structure and spin wave generation even for artificially increased exchange length. The Oersted field influence on onset of precession leading to switching is described in terms of spin wave generation. The switching time as a function of current is found to have nonmonotonic behavior, which is not completely understood but is found to be related to the presence of Oersted field.