Neutron diffraction evidence for a new ferromagnetic phase in Cr doped Pr0.5Ca0.5MnO3

Cr doping in Pr0.5Ca0.5MnO3 is known to destroy the low-temperature antifer romagnetic charge-ordered state and to induce a ferromagnetic component as well as colossal magnetoresistance properties. Effects of Cr doping on the magnetic and nuclear structures are studied here by neutron diffraction for Pr0.5Ca0.5Mn0.95Cr0.05O3. It is shown that, at low temperature, the. stron gly distorted charge ordered structure usually observed in Pr0.5Ca0.5MnO3 i s replaced by a ferromagnetic phase in which the basal-plane distortion of the MnO6 octahedra has disappeared, in agreement with the restoration of th e double-exchange interactions. (C) 1998 American Institute of Physics. [S0 003-6951(98)04951-1].