How spin-orbit torques emerge from materials with weak spin-orbit coupling (e.g., light metals) is an open question in spintronics. Here, we report on a field-like spin-orbit torque (i.e., in-plane spin-orbit field transverse to the current axis) in SiO2-sandwiched permalloy (Py), with the top Py-SiO2 interface incorporating ultrathin Ti or Cu. In both SiO2/Py/Ti/SiO2 and SiO2/Py/Cu/SiO2, this spin-orbit field opposes the classical Oersted field. While the magnitude of the spin-orbit field is at least a factor of 3 greater than the Oersted field, we do not observe evidence for a significant damping-like torque in SiO2/Py/Ti/SiO2 or SiO2/Py/Cu/SiO2. Our findings point to contributions from a Rashba-Edelstein effect or spin-orbit precession at the (Ti, Cu)-inserted interface.
@article{arxiv.1910.08669,
title = {Current-induced spin-orbit field in permalloy interfaced with ultrathin Ti and Cu},
author = {Ryan W. Greening and David A. Smith and Youngmin Lim and Zijian Jiang and Jesse Barber and Steven Dail and Jean J. Heremans and Satoru Emori},
journal= {arXiv preprint arXiv:1910.08669},
year = {2020}
}