STRUCTURAL PECULIARITIES AND PROPERTIES OF (La,Sr)(Mn,Me)O_3 (Me=Cu,Cr)

摘要

Actual oxidation state of doped ions in La_(0.7)Sr_(0.3)Mn_(1-x)Me_xO_(3±δ) systems (Me = Cu, Cr; 0≤x≤0.15) has been determined based on the analysis of structural, magnetic and resonance properties of these materials. It has been shown that for copper-substituted manganites there are two regions of concentrations with different magnetic properties. At x≤0.05 they are homogeneous ferromagnetics with a small variation of magnetic parameters, while at x > 0.05 they become substantially inhomogeneous and both the saturation magnetization and Curie temperature significantly decrease with x increasing. The chromium-substituted compounds are homogeneous ferromagnetics in all investigated concentration range. These results can be explained only in supposition of divalent copper ions and trivalent chromium ones, which was verified and confirmed experimentally.