Mِssbauer study of 57Fe doped LaSrYCu2O6

The Mِssbauer spectra of LaSrYCu1.9757Fe0.03O6 were measured from room temperature to 5K. Room temperature spectrum is a paramagnetic doublet, and IS and QS values suggest that high spin Fe3+ are in octahedral site provided by a excess oxygen, similar to La2SrCu2O6. Below 210K, Mِssbauer spectra become broad, and consist of paramagnetic doublet and magnetic sextet in the wide temperature range. Temperature variation of Hhf suggest that the Néel temperature lies above 200K. The irreversibility and field dependence of susceptibility are observed at low temperatures. By combining the results of the Mِssbauer spectra and magnetic measurements, these behaviors are explained as superparamgnetism of the antiferro spin clusters, and at low temperatures, clusters freeze to the cluster glass like state.