Fig. 3: Dependence on THz pump polarisation angle and ellipticity.
From: Ultrafast unidirectional spin Hall magnetoresistance driven by terahertz light field
a, b SHG intensity in the Ta(2nm)/Py(3nm)/Pt(2nm) sample as a function of the THz pump polarisation angle (ϕ), measured in (a) vertical magnetisation geometry (Fig. 1(c)) and b horizontal magnetisation geometry (Fig. 1d). ϕ = 0 corresponds to the horizontal polarisation. c, d The dependence of SHG intensity on THz pump beam ellipticity, measured in (c) vertical magnetisation geometry and d horizontal magnetisation geometry. The pump beam’s ellipticity was adjusted using a THz quarter-wave plate (QWP) by varying its orientation angle χ from 0° to 90°. The beam polarisation is circular at χ = 45°. The red lines in all graphs depict simulation results that consider the symmetry of \({E}_{ISHE}^{2\Omega }\) and \({E}_{USMR}^{2\Omega }\) signals and are fitted to the experimental data points. In all graphs, the statistical error of the experimental data does not exceed the symbol size.
