Extended Data Fig. 6: Dynamical phase-field simulation results.
a, b, Fourier transform of the simulated polarization dynamics, which is represented by spatially averaged (a) \({P}_{z}^{2}\) and (b) \({P}_{x}^{2}\) in the simulation box on application of the THz-field pulse aligned along the x-, y- or z-axis. c, Calculated frequency spectra of \({P}_{x}^{2}\) with various values of the direct-current (DC) electric field along the x-axis. d, Frequency and amplitude of the vortexon mode as a function of the applied electric field (Ex). Such an in-plane electric field can be applied using a pair of coplanar electrodes, as schematically shown in the inset to d. e, Histograms of the Pb and Sr ionic displacement u away from its equilibrium positions along the x- and z-axes, corresponding to the maximum diffraction intensity change of 4% of 004 SL peak at a delay of 9 ps in the simulation.
