Oxygen Vacancy Induced Metal Insulator Transition in Epitaxial Pr$_{0.7}$Ca$_{0.3}$MnO$_{3}$ Thin Films

We report the metal-insulator transition in epitaxial Pr$_{0.7}$Ca$_{0.3}$MnO$_{3}$ thin film by introducing oxygen vacancies, which assist the nucleation of ferromagnetic metallic domains in a antiferromagnetic insulating matrix. The hysteresis of the resistivity indicates the transition is first-order, and covers a broad temperature range from 80K to 220K. Such novel transport properties of the x=0.3 doped manganite may result from strong spin-lattice coupling which stabilizes the system to a metallic metastable state at low temperature.