Neutron-diffraction study of the magnetic-field-induced metal-insulator transition in ${\mathrm{Pr}}_{0.7}$${\mathrm{Ca}}_{0.3}$${\mathrm{MnO}}_3$

Without a magnetic field ${\mathrm{Pr}}_{0.7}$ ${\mathrm{Ca}}_{0.3}$ ${\mathrm{MnO}}_3$ exhibits three phase transitions: a change of the lattice symmetry at ${\mathit{T}}_{\mathit{B}}$=200 K, an antiferromagnetic ordering at ${\mathit{T}}_{\mathit{N}}$=140 K, and a canted antiferromagnetism at ${\mathit{T}}_{\mathrm{CA}}$=110 K. Although the resistivity of ${\mathrm{Pr}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Ca}}_{\mathit{x}}$ ${\mathrm{MnO}}_3$ shows insulating behavior at zero field, it exhibits an insulator-metal (I-M) transition at around 4.0 T at 5 K. An applied field enforces a ferromagnetic spin alignment and drives ${\mathrm{Pr}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Ca}}_{\mathit{x}}$ ${\mathrm{MnO}}_3$ into the metallic state by actuating the double-exchange mechanism and destroying the charge ordering. This I-M transition at 5 K is accompanied by a large hysteresis.