Fig. 3. Electric polarization and magnetization dynamics.

a, The second-order nonlinear optical susceptibilities $\mathrm{\Delta }{\chi }_{ijk}^{\left(2\right)}\left(t\right)$ (dots), extracted from Fig. 2d,f, are shown as a function of time along with fits (lines) to a damped oscillator model. The curves have been vertically offset for clarity. b, Oscillator energies obtained from the fits indicate separate electromagnon modulations of the C₂-even-like (blue) and C₂-odd-like (red) tensor elements. The frequency obtained from the tr-RKerr signal Δθ_k (see d) at the same pump fluence is also shown. c, Temporal evolution of the electric polarization components ΔP_x and ΔP_y induced by the oscillations of both electromagnon modes compared with the static polarization P₀. Data points (dots) are shown alongside fits of the temporal dynamics (lines). d, tr-RKerr signals for several incident pump fluences at 2.4 K. Experimental data (dots) are shown alongside fits to a damped oscillator model (lines). The curves have been vertically offset for clarity. e, The initial oscillatory phases, Φ, obtained from the fits of the tr-SHG and tr-RKerr signals are shown as a function of incident pump fluence (Supplementary Note 5). All error bars show the 95% confidence intervals obtained from the fits.

Source data