Transport properties in doped Mott insulator epitaxial ${\mathrm{La}}_{1-y}{\mathrm{TiO}}_{3+\delta }$ thin films

We report on the transport properties, Hall effect and resistivity, of epitaxial ${\mathrm{La}}_{1-y}{\mathrm{TiO}}_{3+\delta }$ thin films. The materials, grown by molecular beam epitaxy, display a temperature independent Hall coefficient and a characteristic $T^2$ dependence of the resistivity over a wide temperature range, extending from a few Kelvin to 500 K. These transport properties are shown to be consistent with small polaron metallic conduction with a dominant optical phonon mode whose energy, $ħ{\omega }_0=80\mathrm{}$ K, is characteristic of the tilt/rotation of the oxygen octahedra in perovskite materials.