EPR study of compounds in the LaAlO₃-La_0.67Sr_0.33MnO₃ system

Author： Andronenko S. Andronenko R. Zagrebel’nyi O. Chezhina N.

ISSN： 1087-6596

Source： Glass Physics and Chemistry, Vol.35, Iss.6, 2009-12, pp. : 652-659

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Abstract

The EPR spectra of compounds in the LaAlO₃-La_0.67Sr_0.33Mn_yO₃ system at a frequency of 9.4 GHz have been investigated at the temperatures T = 77 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 Mn²⁺ and Mn⁴⁺ 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 Mn²⁺ and Mn⁴⁺ 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.