Here we introduce a novel, self-calibrated method to determine interfacial spin-orbit torques (SOT) with 250 nm spatial distribution in micrometer wide stripes by magnetization dynamics. Standing spin waves (SSWs) are excited by an rf-current flow in a thin Fe/GaAs layer where the interface induces Rashba- and Dresselhaus-like spin-orbit fields.
The combination of Oersted and Spin-Orbit-Field excitation leads to distinct dynamic mode patterns as a function of applied magnetic field. The precession amplitude is measured by means of time-resolved magneto optical Kerr effect (TR-MOKE) microscopy which allows detailed imaging of the the mode profiles.
Our novel approach is self-calibrated since we can compare the homogeneous SOT with the strength of the Oersted field. The rf-current induces a well-defined inhomogeneous driving torque that allows us to determine the strength of the SOTs. The recorded spatial symmetry is fitted by full micromagnetic simulations to quantify the driving torque strength.