Fig. 3

Current-induced field-like torque. Here we use quadratic MOKE magnetometry to measure current-induced in-plane effective fields in the same configuration as shown in Fig. 2a. In this measurement, normal incidence light with linear polarization along the x-direction is used. Although in this measurement, the polar MOKE signal is also detected, it is much weaker than the quadratic MOKE response and can be distinguished from fittings. a The quadratic MOKE response measured in the test and control samples when current is applied parallel to H _ext. No dependence on the initial magnetization of the PML, \(\hat {\bf{m}}\), is observed. b The quadratic MOKE response measured in the test and control samples when current is applied perpendicular to H _ext. In the test sample, the quadratic MOKE response is reversed when \(\hat {\bf{m}}\) is reversed. On the contrary, the weak quadratic MOKE response in the control sample, which is likely due to small misalignment of H _ext, has little dependence on \(\hat {\bf{m}}\). c The angle dependence of \({{\psi }}_{{\rm{quad}}}^{{\rm{even}}}\) and \({{\psi }}_{{\rm{quad}}}^{{\rm{odd}}}\) of the test sample. Here the values are extracted by performing a linear fitting with \({{\psi }}_{{\rm{quad}}}^{{\rm{cal}}}\), which is the quadratic MOKE response measured with an external AC calibration field of 117±10 Am⁻¹. The slope is extracted and plotted here as \({{\psi }}_{{\rm{quad}}}^{{\rm{even}}}{\rm{/\psi }}_{{\rm{quad}}}^{{\rm{cal}}}\) and \({{\psi }}_{{\rm{quad}}}^{{\rm{odd}}}{\rm{/\psi }}_{{\rm{quad}}}^{{\rm{cal}}}\), respectively. Red lines are fittings with \({{\psi }}_{{\rm{quad}}}^{{\rm{even}}}{\rm{/\psi }}_{{\rm{quad}}}^{{\rm{cal}}} = 0.95\,{\rm{cos}}\left( {\frac{\pi }{{180}}\phi } \right)\) and \({{\psi }}_{{\rm{quad}}}^{{\rm{odd}}}{\rm{/\psi }}_{{\rm{quad}}}^{{\rm{cal}}} = 0.35\,{\rm{sin}}\left( {\frac{\pi }{{180}}\phi } \right)\). The error bars represent the standard deviation associated with the linear fitting performed on \({{\psi }}_{{\rm{quad}}}^{{\rm{cal}}}\)