Crystal growth, transport and magnetic properties of rare-earth manganite Pr1-xPbxMnO3Pr1-xPbxMnO3

Crystal growth, electrical and magnetic properties are reported for mixed valence manganite Pr1-xPbxMnO3Pr1-xPbxMnO3 (x=0.2,0.23x=0.2,0.23, and 0.3). The crystals with x=0.2x=0.2 and 0.23 are ferromagnetic and insulating, whereas that with x=0.3x=0.3 is ferromagnetic below 200 K and shows an insulator–metal transition at 235 K. This composition shows a magnetoresistance of 90% in a field of 5 T. In the paramagnetic region, the temperature dependence of magnetic susceptibility of the crystals follows a Curie–Weiss behavior. The thermal evolution of magnetization in the ferromagnetic phase varies as T3/2T3/2, in accordance with Bloch's law. The spin-stiffness constant DD obtained from the Bloch constant is found to increase linearly with x. The magnetization does not reach complete saturation upto a field of 5 T. A possible contribution of the Pr spins to the total magnetic moment is discussed.