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

TL;DR

This study investigates how annealing affects the interfacial Dzyaloshinskii-Moriya interaction in Ta/CoFeB/MgO trilayers, revealing a peak at 230°C linked to interfacial crystal ordering and B expulsion.

Contribution

It demonstrates that annealing can modulate the DMI in Ta/CoFeB/MgO, highlighting the relationship between annealing temperature, interfacial structure, and magnetic interactions.

Findings

DMI peaks at 230°C annealing temperature.

DMI and anisotropy fields follow similar trends with annealing.

Interfacial crystal ordering and B expulsion influence DMI behavior.

Abstract

The interfacial Dzyaloshinskii-Moriya interaction (DMI) has been shown to stabilize homochiral N\'eel-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 $D=0.057\pm0.003$ 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.