Artifact-free optical spin–orbit torque magnetometry

Abstract

Here, we demonstrate an optical spin–orbit torque (SOT) measurement scheme that is free from artifacts such as the optic planar Hall effect (PHE) and the optic anomalous Nernst effect (ANE). Such PHE and ANE signals complicate the SOT analysis in the electrical harmonic measurement method. Our optical setup utilizes photoelastic modulation and balanced detection to measure the polar magneto-optic Kerr effect (pMOKE) signal exclusively. We verified the separation of the pMOKE signal in the Pt/Py bilayer sample with a sizable optic PHE. Our method uses a single measurement principle and reduces the analysis complexity, and thus could help expand the scope of SOT studies.