Structure-related transport properties of A-site ordered perovskite   Sr3ErMn4-xGaxO10.5-d
  We report x-ray diffraction, resistivity, thermopower, and magnetization of Sr3ErMn4-xGaxO10.5-d, in which A-site ordered tetragonal phase appears above x=1, and reveal that the system exhibits typical properties seen in the antiferromagnetic insulator with Mn3+. We succeed in preparing both A-site ordered and disordered phases for x=1 in different preparation conditions, and observe a significant decrease of the resistivity in the disordered phase. We discuss possible origins of the decrease focusing on the dimensionality and the disordered effect. 
W. Kobayashi, and T. Ishibashi
cond-mat.mtrl-sci