Fig. 4. Electromagnon dynamical magnetoelectric coupling.
a, Time-dependent modulations of the two-dimensional electric polarization and magnetization extracted for EMo from the tr-SHG (blue dots, lines) and tr-RKerr measurements (red dots, lines). Theoretical electric polarization and magnetization dynamics of the EMo mode obtained from DFT calculations and presented assuming a phenomenological damping rate (filled areas). To clarify the oscillatory dynamics, the experimental data were interpolated by a factor of 2 and then smoothed with a moving average filter. b, The dynamical magnetoelectric coupling constant α(ω) in the terahertz spectral range retrieved in a variety of materials (Supplementary Table 7). Data points are categorized by their associated optical rotational phenomena. NOA, natural optical activity (blue circles); GB, gyrotropic birefringence (red triangles).