Fig. 2: USMR-SHG symmetry.
From: Ultrafast unidirectional spin Hall magnetoresistance driven by terahertz light field
a, b SHG amplitude in a Ta(2nm)/Py(3nm)/Pt(2nm) and b Ta(2nm)/Co(2nm)/Pt(2nm) samples, measured in the vertical magnetisation geometry (cf. Fig. 1c) with the THz pump pulse polarised perpendicular (horizontal pump, black curve) and parallel (vertical pump, red curve) to the Py and Co magnetisation direction. The EOS and WG are adjusted to detect only the horizontal polarisation components of the SHG signal. c Comparison of SHG signals in the Ta(2nm)/Py(3nm)/Pt (2nm) sample for two opposite magnetisation directions. Signals were measured in the horizontal magnetisation geometry (Fig. 1d), with the THz pump polarised at ϕ = 45° with respect to the magnetisation plane. The 180° phase shift in the signal indicates its odd behaviour under the inversion of the magnetisation direction. d Comparison of the SHG signals from Py(2nm)/Pt(3nm) and Py(2nm)/W(3nm) samples measured in the same geometry as in (c). The observed 180° phase shift between the signals of the two samples is ascribed to the opposite signs of the spin Hall conductivity in Pt and W.
