Assessment of Rashba Field Effects in Ultrathin Pt/Co/GdOx Submicrometer Strips

Abstract

The influence of injected current on magnetization dynamics is investigated in submicrometer-wide strips of out-of-plane magnetized Pt/Co/GdOx. This ultrathin film structure is similar to Pt/Co/AlOx exhibiting highly efficient current-driven domain wall (DW) motion, which has recently been attributed in part to the Rashba effect. In Pt/Co/GdOx, the reduction of the out-of-plane magnetization with increasing injected current is largely due to Joule heating, and the effective transverse Rashba field that tilts the magnetization is estimated to be at most T/( A/m ). Measurements of high-speed DW motion reveal no evidence of a strong Rashba field to suppress DW precession. These findings indicate that the Rashba effect plays a limited or negligible role in current-driven DW dynamics, and alternative torques are required to explain the high efficiency of DW motion in ultrathin heavy-metal/ferromagnet/oxide systems.

Large voltage-induced modification of spin-orbit torques in Pt/Co/GdOx

“…Since the measurement timescale is much slower than precessional dynamics, the SOTs can be considered in terms of effective magnetic fields, 34,35   Magneto-optical detection has recently been used in Ref. 36 to probe field-like SOTs and by Fan et al to quantify vector SOTs in in-plane magnetized bilayer thin films. 37 This optical detection method does not suffer from a thermoelectric (anomalous Nernst effect) artifact that may be substantial in the anomalous Hall voltage technique, nor does it suffer from signal contamination due to the planar Hall effect contribution.…”