Domain wall nucleation and propagation in spin-transfer torque switching with thermal effects

Publication date: Available online 3 October 2018Source: Physics Letters AAuthor(s): Bingjin Chen, Tiejun Zhou, Siang Yee Sim, Sze Ter Lim, Hao GongAbstractWe conduct micro-magnetic simulations to study spin-transfer torque induced magnetization switching in perpendicular magnetic tunneling junctions. The effects of current densities and temperatures on the switching processes are studied in details. We then proposed an approach to compute the deterministic switching time by taking thermal-effect into account. The switching time is less temperature-dependent under higher current density; however, as the current density decreases, the effect of temperature on the switching time becomes more and more significant. The switching process with micro-magnetic simulations is shown to be via domain wall nucleation and propagation. The phenomena are consistent with the recent experimental found-out. We further propose a method to compute the switching time based on domain wall nucleation and propagation theory, and compare the switching time with those from macro-spin approximation. It is found the switching times from the micro-magnetic simulations are much shorter than that from the macro-spin approximations. Macro-spin approximation over-estimates the switching times due to its coherent rotation assumptions.

Source: Physics Letters A - October 5, 2018 Category: Physics Source Type: research