Conductivity jumps and low-temperature magnetoresistance in new semiconducting La1-xBixMnO3+δ perovskites
Perekalina T.M., Gubkin M.K., Shapiro A.Ya., Chubaren ko V.A.
The abrupt jumps were observed on the temperature dependences of electrical conductivity of Ltt]-xBixMaOi+g (0.1<x<0.7) and Lao.3Bio.7Nao.! íÐïÚ+$ ceramics. The temperatures at which the jumps take place could be reduced by several degrees at applying external magnetic field of 15 kOe. It can be seen from the magnetization data that low-temperature poor-conducting phase is not antiferromagnetic (it is likely ferromagnetic) and hence the real-space charge ordering mechanism is not sufficient for explaining the experimental results. An interpretation in terms of magnetic phase nonuniformity is proposed. All the samples studied showed high low-temperature magnetoresistance. PACS: 71.27.+a, 71.28.+d, 71.30.-l-h, 75.30.Kz