Current-induced magnetization switching through spin-orbit torques (SOTs) is the fundamental building block of spin-orbitronics. The SOTs generally arise from the spin-orbit coupling of heavy metals. However, even in a heterostructure where a metallic magnet is sandwiched by two different insulators, a nonzero current-induced SOT is expected because of the broken inversion symmetry; an electrical insulator can be a spin-torque generator. Here, we demonstrate current-induced magnetization switching using an insulator. We show that oxygen incorporation into the most widely used spintronic material, Pt, turns the heavy metal into an electrically-insulating generator of the SOTs, enabling the electrical switching of perpendicular magnetization in a ferrimagnet sandwiched by electrically-insulating oxides. We further found that the SOTs generated from the Pt oxide can be controlled electrically through voltage-driven oxygen migration. These findings open a route towards energy-efficient, voltage-programmable spin-orbit devices based on solid-state switching of heavy metal oxidation.
@article{arxiv.1709.07127,
title = {Current-induced magnetization switching using electrically-insulating spin-torque generator},
author = {Hongyu An and Takeo Ohno and Yusuke Kanno and Yuito Kageyama and Yasuaki Monnai and Hideyuki Maki and Ji Shi and Kazuya Ando},
journal= {arXiv preprint arXiv:1709.07127},
year = {2017}
}