Crystal growth, transport and magnetic properties of rare-earth manganite [formula omitted

Abstract

Crystal growth, electrical and magnetic properties are reported for mixed valence manganite Pr 1 - x Pb x MnO 3 ( x = 0.2 , 0.23 , and 0.3). The crystals with x = 0.2 and 0.23 are ferromagnetic and insulating, whereas that with x = 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 T 3 / 2 , in accordance with Bloch's law. The spin-stiffness constant D 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.