Dynamics of the bipyramidal ions in SrFe12O19studied by Mossbauer spectroscopy

The dynamics of the bipyramidal Fe sites in SrFe 12 O 19 is investigated. Using single crystal Mossbauer spectroscopy data, the authors have shown that these Fe ions diffuse rapidly between two pseudo-tetrahedral sites (4e) in a wine-bottle-shaped potential at any temperature (70-300 K). The effective recoilless fraction associated with the 4e sites is described in terms of a self-interference mode, which provides a measure of the jumping distance. It is found that the jumping distance strongly decreases when the temperature is decreased. The room-temperature data are in excellent agreement with the available X-ray diffraction data.