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 (∼1010%) 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.