Magnetic and transport properties of lanthanum perovskites with B-site half doping

We have synthesized various half doped lanthanum perovskites LaB 0.5 B 0.5 ′ O 3 (BB′=MnV, MnCr, MnCo, MnNi, FeCr, FeMn, FeCo, FeNi) by solid state reaction method. The crystal structure was orthorhombic in all samples, but the magnetic and transport properties showed a large variation with the composition. A ferromagnetic feature was quite strong in the Mn-based perovskites but weak or non-existent in the Fe-based ones. The resistivity of Ni-doped ones was much smaller than those of the others. For all half doped perovskits, remarkably, the temperature dependent transport was well explained by variable range hopping model with different localization lengths.