B-site bismuth doping effect on structural, magnetic and magnetotransport properties of La0.5Ca0.5Mn1−xBixO3

We report the structural, magnetic and magnetotransport properties of polycrystalline La0.5Ca0.5Mn1−xBixO3 (x=0, 0.02 and 0.05). Refinement of X-ray powder diffraction patterns shows that all samples crystallize with orthorhombic Pnma space group. For x=0.02, the sample shows an increase of unit cell volume as well as Curie temperature TC with the destruction of charge ordering (CO) state existing in parent compound. With 5% bismuth at the B-site, unit cell volume and TC decrease with an enhancement of CO state. Bismuth doping induces a spin glass like state at low temperature with the presence of Griffiths phase above TC. Magnetoresistance (MR) measurements show typical negative colossal magnetoresistance (CMR) at low temperature.