Effect of annealing on the interfacial Dzyaloshinskii-Moriya interaction in Ta/CoFeB/MgO trilayers

Abstract

The interfacial Dzyaloshinskii-Moriya interaction (DMI) has been shown to stabilize homochiral Néel-type domain walls in thin films with perpendicular magnetic anisotropy and as a result permit them to be propagated by a spin Hall torque. In this study, we demonstrate that in Ta/Co${}_{20}$Fe${}_{60}$B${}_{20}$/MgO the DMI may be influenced by annealing. We find that the DMI peaks at $D=0.057\pm 0.003$ mJ/m${}^2$ at an annealing temperature of 230 ${}^{\circ }$C. DMI fields were measured using a purely field-driven creep regime domain expansion technique. The DMI field and the anisotropy field follow a similar trend as a function of annealing temperature. We infer that the behavior of the DMI and the anisotropy are related to interfacial crystal ordering and B expulsion out of the CoFeB layer as the annealing temperature is increased.

5 pages and 4 figures