Magnetic-field-induced metal-insulator transition in Pr0.7Ca0.3MnO3

A field-induced insulator-metal (I-M) transition in Pr0.7Ca0.3MnO3 has been studied with neutron diffraction experiments. Over the whole temperature range, the resistivity of Pr0.7Ca0.3MnO3 shows insulating behavior at zero field, but exhibits an I-M transition at around 4.0 T at 5 K. It has been established that an applied field enforces a ferromagnetic spin alignment and drives Pr0.7Ca0.3MnO3 to a metallic state by actuating the double exchange mechanism and destroying the charge ordering. This I-M transition at 5 K is accompanied with a large hysteresis. By contrast, in the field dependence at 50 K, antiferromagnetic and charge-order components are gradually recovered below 2.0 T in a field-decreasing process. Furthermore, a reentrant I-M-I transition has been observed in the temperature dependence at 2.5 T.