MOSSBAUER STUDY OF FE-57 DOPED LASRYCU2O6

The Mossbauer spectra of (LaSrYCu1.97Fe0.03O6)-Fe-57 were measured fro m room temperature to 5K. Room temperature spectrum is a paramagnetic doublet, and IS and QS values suggest that high spin Fe3+ are in octah edral site provided by a excess oxygen, similar to La2SrCu2O6. Below 2 10K, Mossbauer spectra become broad, and consist of paramagnetic doubl et and magnetic sextet in the wide temperature range. Temperature vari ation of H-hf suggest that the Neel temperature lies above 200K. The i rreversibility and field dependence of susceptibility are observed at low temperatures. By combining the results of the Mossbauer spectra an d magnetic measurements, these behaviors are explained as superparamgn etism of the antiferro spin clusters, and at low temperatures, cluster s freeze to the cluster glass like state.