Sensitive measurement of spin-orbit torque driven ferromagnetic resonance detected by planar Hall geometry

Abstract

The magnetization of a nano-magnet can be manipulated and even switched by spin-orbit torques. Hence, accurate characterization of these torques is essential from the application perspective. In this work, we present an alternative method to characterize the spin-orbit torque utilizing the planar Hall effect of a ferromagnet. We show that while the ferromagnet is excited to resonance due to spin-orbit torque, its planar Hall resistance also varies, which leads to sensitive detection of spin-orbit torque. We further demonstrate that planar Hall geometry enables us to estimate spin Hall angle measuring change in magnetic damping very accurately while rf current and dc current are applied perpendicular to each other. Using these techniques, we show that in the Pt/Py bilayer, the spin-Hall effect dominates over interfacial field like spin-orbit torques, which is consistent with previous studies.