Metal-Insulator Transition in (La_0.7Sr_0.3Mn_0.98Co_0.02O₃)_1−x(BaTiO₃)_x Multiferroic

抄録

(La_0.7Sr_0.3Mn_0.98Co_0.02O₃)_1−x(BaTiO₃)_x (x = 0.1; 0.2; 0.3) mixed perovskite were prepared by the solid state reaction method. It is shown that this compound exposes the multiferroic (magnetic and ferroelectric) behavior comparing with magnetic pristine La_0.7Sr_0.3Mn_0.98Co_0.02O₃. The increase of BaTiO₃ fraction from x = 0.1 to 0.3 leads to weakening (enhancing) of the ferromagnetic (ferroelectric) order. The metal-insulator transition (MIT) in the ferromagnetic La_0.7Sr_0.3Mn_0.98Co_0.02O₃ (x = 0) and the multiferroic x = 0.1, 0.2 samples were registered with reduction of the MIT temperature T_MI from 380 K of the x = 0 to 117 K of the x = 0.2 samples. Temperature dependence of resistivity and MIT of these samples are well described by the mixed conducting carrier model, which has crossover between the low temperature spin-scattering electron and the hopping small polarons conductions at T_MI.

Fig. 8 Temperature dependence of the volume fraction functions for metallic like (f) and small polaron (1 − f) electrical carriers in x = 0 (a), x = 0.1 and 0.2 samples (b).