Chemical disorder effects in transport and magnetic properties of perovskite manganite

摘要

The dependence of the novel properties observed in colossal magnetoresistance (CMR) materials, other than average ionic radii (r_A) and Mn valence ratio (Mn~(3+)/Mn~(4-)), was investigated through examination of the transport and magnetic properties of Pr_(0.65)(Ca_(0.7)Sr_(0.3))_(0.35)MnO_3, La_(0.123)Pr_(0.527)(Ca_(0.8)Sr_(0.2))_(0.35)MnO_3, and Pr_(0.65)(Ca_(0.866)Ba_(0.134))_(0.35)MnO_3. The average ionic radii (r_A) and valence ratio of all three samples have been kept equal. The results of this investigation indicate a more intense role of the nature of individual A-site cation and the lattice mismatch. A remarkably large magnetoresistance of the order of 10~8 at moderate magnetic field has been observed for Ba-doped sample.