Colossal magnetoresistance in perovskite manganite induced by localized moment of rare earth ion

The magnetic and transport properties of a single crystal of Pr0.7Ca0.3MnO3 annealed by various magnetic fields were investigated by dc and ac magnetization measurements. The ordered Pr moment is almost absent in zero-field magnetization but is clearly observed when the sample was measured after annealing with a magnetic field. The Pr moment is enhanced when the annealing field is increased. Remarkably, the ordered Pr spins appear to induce colossal magnetoresistance (similar to 10(10)%) as well as a metal-insulator (M-I) transition in Pr0.7Ca0.3MnO3. This unique behavior is discussed in terms of the reorientation of Pr spins that are strongly coupled with the neighboring Mn spins. (C) 2003 Elsevier Science Ltd. All rights reserved.