Figure 7
\(^{57}\)Fe Mössbauer spectra (experimental hollow dots) recorded at (a) 300 K (above \(T_\mathrm {N}\)) and (b) 15 K (below \(T_\mathrm {N}\))25. Solid lines are simulation of the experimental spectra as described in the text. (c) Directions of the electric field gradient (EFG) tensor principal axes (\(V_{ii}\)) and the hyperfine magnetic field (\(B_\mathrm {hf}\)) for Fe(1), Fe(2), and Fe(3) sites. The atomic coordinate of the Fe atoms shown in the Figure corresponds to(0.75, 0.75, 0.66383), (0.75, 0.25, 0.28279) and (0.53556, 0.12435, 0.97663) for Fe(1), Fe(2), and Fe(3) sites, respectively. Note that the direction of \(V_{YY}\) at Fe(1) and Fe(2) sites is exactly along the c-direction because of the twofold rotation around the c-axis.
