EPR Study of Compounds in the LaAlO3-La_(0.67)Sr_(0.33)MnO3 System

摘要

The EPR spectra of compounds in the LaA1O3-La_(0.67)Sr_(0.33)Mn_yO3 system at a frequency of 9.4 GHz have been investigated at the temperatures T =11 and 300 K as a function of the manganese concentration y (y = 0.015, 0.030, 0.080). It has been revealed that, in the paramagnetic state at y = 0.015, there exist isolated Mn~(2+) and Mn~(4+) ions, which has been confirmed by simulating the EPR spectra. The parameters of the EPR spectra have been determined. The effective magnetic moments μ_(eff) of the Mn~(2+) and Mn~(4+) ions have been calculated from the EPR spectra. It has been demonstrated that an increase in the Mn concentration leads to a decrease in the number of isolated ions and to the formation of new spin clusters. This manifests itself in the predominance of a broad line with weak traces of the hyperfine structure due to the isolated manganese ions.