Magnetic and Electronic Transport Properties of CaMn_1-xNb_xO₃

Abstract

Polycrystalline CaMn1-xNbxO3 compounds (x = 0.1, 0.2, 0.3) were synthesized by a solid reaction. CaMn1-xNbxO3 crystallizes in an orthorhombic GdFeO3-type structure. The Nd doping causes the increases of the lattice parameters, unit cell volume, the average Mn−O bond distance, and Mn−O−Mn bond angle. CaMn1-xNbxO3 compounds show magnetic phase inhomogeneity. With increasing the Nb concentration, CaMn1-xNbxO3 compounds exhibit ferromagnetic, metamagnetic, antiferromagnetic, and paramagnetic characterizations, respectively. And their magnetizations significantly reduce. CaMn1-xNbxO3 compounds are insulators in the temperature range from 5 to 400 K, and their resistivities enhance with increasing Nb content. A huge asymmetry resistivity hysteresis loop is observed for the CaMn0.9Nb0.1O3 compound at low temperature; however, this resistivity loop is melting with increasing the applied field and temperature and tends to disappear near the Curie temperature. This phenomenon might be due to the Nb doping inducing a low-temperature magneto-electric phase separation between the ferromagnetic metallic and the charge-ordering antiferromagnetic insulating phases.