Studies on Crystal Structure and Magnetic Scaling Behavior of Perovskite-Like (La_(1-X)Pb_x)MnO_3 System with x = 0 - 0.5

摘要

The magnetic critical behaviors in the perovskite-like (La_(1-x)Pb_x)MnO_3 series with x = 0.0 ～ 0.5 are studied by means of dc magnetic measurements. All the samples crystallize in the rhombohedral unit cell with a R3C space group (a ～ 0.54 nm and c ～ 1.33 nm). The detailed crystallographic parameters of all the samples are obtained by the refinements of the powder x-ray diffraction data using the Rietveld method. The substitution effect of Pb~(2+) ions on La~(3+) sites induces a mixed-valence state of Mn~(3+)/Mn~(4+) and enhances magnetic transition temperature in the (La_(1-X)Pb_x)MnO_3 system. The transition temperature T_C increases with the Pb content from 225 K as x = 0 to 355 K as x = 0.5. The canonical spin-glass behaviors in low fields and the scaling behaviors of magnetic physical quantities are clearly observed in all our samples. The values of the related critical exponents and the scaling functions of magnetic data are close to those of the conventional spin glass systems.