Enhancement of spin-orbit torque and modulation of Dzyaloshinskii-Moriya interaction in Pt100-xCrx/Co/AlOxtrilayer

Abstract

Alloying a heavy metal (HM) layer is a useful approach to enhance the current-spin converting efficiency ζSH while keeping a relatively low resistance for spin-orbit torque (SOT) based devices. In this work, we report the enhancement of ζSH and nonlinear modification of the Dzyaloshinskii-Moriya interaction (DMI) by alloying Pt with Cr in a Pt100-xCrx/Co/AlOx trilayer. The maximum of ζSH is found at the composition of Pt75Cr25. At the compositions of Pt75Cr25 and Pt50Cr50, the DMI constant |D| is strongly shifted in the opposite sign, implying ferromagnetic coupling and antiferromagnetic coupling existing in the heavy metal layer can both influence the DMI. Finally, the current-driven switching behavior is observed by the magneto-optical effect. This work shows that adjusting the composition of the magnetic alloyed HM layer is an efficient approach to obtain an optimized SOT performance.