Fig. 2: Study of various experiment geometries in optical pump-THz emission from Mn₃Sn.

Normalised THz emission amplitude S_x(φ) and S_y(φ) data sets measured in configuration 2 and configuration 3 are plotted in (a, b) respectively. The sample was rotated around the x-axis by θ_x = + 25° ± 5° or θ_y = + 15° ± 2° respectively. c shows THz signals measured along y in configuration 3 for tilting angles θ_y between 0 and 30°. The data sets were fitted with Eq. (1) to extract the values of ∣h_y∣ and ∣l_y∣ parameters, respectively the magnitude of the circular polarisation helicity-dependent component and the near polarisation-dependent component. d shows even (see Eq. (2)) and odd (see Eq. (3)) responses with respect to θ_y, the rotation angle around the y-axis. The figure displays normalised THz signals measured along y in configuration 3. All measurements in (a–d) were performed at room temperature with no magnetic field. Data sets shown in (a, b–d) were fitted with Eq. (1) prior to normalisation to subtract the polarisation-independent backgrounds, B_i.