The directories 001 and 100 contain the Fourier transform µSR spectra measured for each of these orientations at 40 K.
The temperatures and fields for which each of these spectra correspond to is included in the filename

The files 001-peaks.dat and 100-peaks.dat include the fitted values of the peak centres shown in Figs 3(d) and (h), respectively.
In each file the first column gives the applied magnetic field in Tesla.
The remaining columns give the value and associated error of the peak positions (measured relative to B0).

The file fits.dat gives the results of the fits to the field shifts in Fig.3(h).
The format of the file is
B0 (T), negative field shift (T), positive field shift (T), Gd moment (Bohr magnetons)

MvH_40K.dat contains the moment measured using magnetometry as a function of applied magnetic field. The format is
Applied field (T), Gd moment (Bohr magnetons)

chi.dat contains the ac susceptibility data used to generate Fig.3(j). The format is
T (K), B(T), log(chi' (emu/Oe)) 