Fig. 4: Ultrafast signatures of magnetophononic coupling.

a Schematic of pump-probe measurement. b Pump-induced changes in the transient reflectivity (ΔR/R) as a function of time delay at various magnetic fields, normalized to the maximum amplitude. The black line is a representative biexponential fit to the 0 T data. c The residual ΔR/R upon subtracting a biexponential fit. d Residual ΔR/R at 0 T, with black dots denoting experimental datapoints and the gray line denoting the fit to the sum of two decaying sinusoidal functions. e Individual decaying sinusoidal components obtained from the fit in (b), corresponding to the A_1g⁽¹⁾ (top) and A_1g⁽²⁾ (bottom) phonons, respectively. f Initial amplitude of the coherent A_1g⁽¹⁾ and A_1g⁽²⁾ phonons, obtained from fit result in (d). The gray line is the antiferromagnetic order parameter from reference¹⁵. g Measured transient electron diffraction intensity of the (2 2 0) Bragg peak, with black dots denoting experimental datapoints, and the black line denoting the fit to an exponential decay function. Error bars are standard deviations in fit values.