Chiral-triggered magnetization switching in patterned media

Abstract

The current triggered switching of patterned ferromagnetic elements over a heavy metal layer is analyzed in this work. A couple of symmetrically placed, but isolated, U-shaped elements, each one consisting of two oppositely tilted tapered spikes at the ends of a straight section, is theoretically studied by means of micromagnetic simulations. Our results indicate that the magnetization reversal processes deterministically start at a corner of the spikes selected by the direction of the current, as other experimental evidences claimed. Our study also reveals that the thermal agitation plays a supporting rather than a main role in promoting complete switching. Temperature assists the local magnetization reversal at the corners, resulting in the nucleation of domain walls. This inversion is mainly due to the Slonczewskii-like torque exerted by the spin current associated with the spin Hall effect. When domain walls are nucleated, the angular dependence of the current-driven dynamics of those walls, already reported in the literature, determines whether the process results in either a complete or a frustrated switching attempt. Besides, our statistical study reflects that complete switching is only achieved within a narrow range of current pulse amplitudes.