Fig. 2: Results of the time-resolved resonant SAXS experiment following the laser-driven dynamics of magnetic domains in the FeGd multilayer.

a The q-dependent, transient SAXS intensity, I(q, t), at the Fe L₃ absorption edge at an incident fluence of 25 mJ/cm². Data are averaged for three selected delay intervals A, B, and C as indicated by shaded areas in panel b and then fitted by a Γ-distribution (lines). The grey dashed line indicates the peak position before photoexcitation. b Extracted magnetisation and relative peak shift in dependence of pump–probe delay. Data are fitted by the sum of three exponential functions to extract the relevant time scales (lines). c Differences of the SAXS intensities, I(q, t), for better visualisation of the peak shift. The data and fits from panel a are normalised by their respective peak intensities before subtracting the data before photoexcitation (A) from the data at positive peak shift (B, blue) and negative peak shift (C, red). Markers refer to differences of the experimental data, and lines refer to the differences of the fits. Data points were additionally smoothed by a running average. d, e Delay scans of the transient magnetisation, M(t), probed at the two absorption edges Fe L₃ (d) and Gd M₅ (e) for a series of excitation fluences. The data is fitted by a double-exponential function to extract the relevant time scales. All error bars correspond to the statistical standard error of the mean