We report optical, electrical and magnetotransport properties of oxygen deficient ${\mathrm{SrTiO}}_3$ (${\mathrm{SrTiO}}_{3-x}$) thin films fabricated by pulsed laser deposition technique. The oxygen vacancies (${\mathrm{O}}_{\mathrm{vac}}$) in the thin film are expected to be uniform. By comparing its electrical properties to those of bulk ${\mathrm{SrTiO}}_{3-x}$, it was found that ${\mathrm{O}}_{\mathrm{vac}}$ in bulk ${\mathrm{SrTiO}}_{3-x}$ is far from uniform over the whole material. The metal-insulator transition (MIT) observed in the ${\mathrm{SrTiO}}_{3-x}$ film was found to be induced by the carrier freeze-out effect. The low temperature frozen state can be reexcited by Joule heating, electric and intriguingly magnetic field.

• Received 20 April 2011

DOI:https://doi.org/10.1103/PhysRevLett.107.146802