Preparation, magnetic and transport properties of A0.66Ba0.34MnO3-γ (A = Pr, Nd, Sm, Eu, Gd) perovskites

The manganites A(0.66)Ba(0.34)MnO(3-gamma) (A = PZ Nd, Sm, Eu, Gd) with cubic perovskite structure have been synthesized. It is found that Pr0.66Ba0.34MnO3 and Nd0.66Ba0.34MnO3 are ferromagnets while Sm-, Eu-and Gd-containing samples exhibit spin-glass-like behavior. The decreasing oxygen content in A(0.66)Ba(0.34)MnO(3-gamma) (A = Pr, Nd) up to gamma = 0.1 leads to the collapse of the long-range ferromagnetic order. The Nd0.66Ba0.34MnO3 exhibits giant magnetoresistance below T-e similar to 150 K. The results can be explained in terms of the model of superexchange interactions via oxygen. (C) 1997 Elsevier Science B.V. All rights reserved.