A M\"ossbauer study of the magneto-structural coupling effect in SrFe${}_2$As${}_2$ and SrFeAsF

In the present paper, we report a comparison study of SrFe${}_2$As${}_2$ and SrFeAsF using M"ossbauer spectroscopy. The temperature dependence of the magnetic hyperfine field is fitted with a modified Bean-Rodbell model. The results give much smaller magnetic moment and magneto-structural coupling effect for SrFeAsF, which may be understood as due to different inter-layer properties of the two compounds.