Fig. 4: Numerical solutions of the ultrafast dynamics of the order parameter based on the time- and spatially-dependent Ginzburg-Landau model.

a Order parameter as a function of delay time and depth z away from the sample surface at a fluence of η = 4. b Schematic to show the phase-inversion induced interfacial CDW without lattice distortion. The solid lines indicate the amplitude of the atomic displacements. c Order parameter of the surface (z = 0) as a function of delay time for selected pump fluences η. d Simulated fluence-dependent suppression time of the CDW order (top) and intensity of the amplitude mode (middle), along with experimental fluence-dependent integrated intensity of the amplitude mode at a frequency of 2.15 THz (bottom) from Fig. 2f. The inset zooms in panel c between 0 and 0.6 ps. e Fluence-dependent order parameter (top) and energy potential V(Φ) (middle) at a delay time of 6 ps, along with experimental fluence-dependent energy shifts (bottom) at the same delay time from Fig. 3c. The x-axes in d and e are normalized to match the experimental and calculated data.