Optical Conductivity Studies of Small Polaron Hopping in Sm$_{\mathrm{1-x}}$Sr$_{\mathrm{x}}$TiO$_{3}$ Epitaxial Films

ORAL

Abstract

We present our findings in the optical conductivity in a doping-controlled metal-to-Mott-insulator transition. These samples, grown using hybrid MBE, span the transition from the Mott insulator SmTiO$_{3}$ to metallic, lightly-doped SrTiO$_{3}$. Zhou and Goodenough have studied a wide range of rare earth titanates and found that SmTiO$_{3}$ has thermally activated transport. We plan to measure the optical conductivity of doped samples to determine the conduction mechanism. Using FTIR spectroscopy, we extract the optical conductivity in the 0.06-2.5 eV range. If conduction in Sm$_{\mathrm{1-x}}$Sr$_{\mathrm{x}}$TiO$_{3}$ is due to small polarons, it will have a distinct optical conductivity feature, related to the DC transport, as described by David Emin. Alternatively, conduction could be due to variable-range hopping between defects. Further, from the combination of DC and optical conductivity, we can also test the prediction of Yee and Balents that the metal-to-insulator transition is first-order with percolative phase separation between metallic and localized regions. Such a sample would have a distinct Drude tail plus polaron contributions to its conductivity.

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Authors

  • William Flaherty

    UC Santa Barbara

  • V.V. Shlyaptseva

    California State University, Dominguez Hills, Univ of California - Irvine, University of Chicago, UC Merced, NINT, Dublin Institute of Technology, Ireland, MIT, NASA/GSFC, CRESST/UMBC \& NASA/GSFC, LLNL, MPI for Plasma Physics, Remeis-Sternwarte/ECAP/FAU, Humboldt State University, University of Nevada Reno, The University of Michigan, University of Nevada, Reno, Lawrence Livermore National Laboratory, Sandia National Laboratories, Los Alamos National Laboratory, Laboratory for Laser Energetics, University of Rochester, Univ of Nevada - Reno, University of Nevada, Reno - Physics Department, Jilin University, China, Department of Physics, University of California, Berkeley, Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Advanced Materials Laboratory, National Institute for Materials Science, Department of Physics \& Astronomy, California State University, Long Beach, CA 90840, UC Santa Barbara, Department of Physics and Astronomy, University of California, Riverside, University of California at Merced, Laboratoire de Physique des Plasmas (CNRS/Ecole Polytechnique/UPMC/Universit\'e Paris Sud), Ecole Polytechnique, 91128 Palaiseau, France, University of Nevada, Reno, NV 89557, USA, University of Nevada, Reno, NV 89557 USA, University of Nevada-Reno

  • V.V. Shlyaptseva

    California State University, Dominguez Hills, Univ of California - Irvine, University of Chicago, UC Merced, NINT, Dublin Institute of Technology, Ireland, MIT, NASA/GSFC, CRESST/UMBC \& NASA/GSFC, LLNL, MPI for Plasma Physics, Remeis-Sternwarte/ECAP/FAU, Humboldt State University, University of Nevada Reno, The University of Michigan, University of Nevada, Reno, Lawrence Livermore National Laboratory, Sandia National Laboratories, Los Alamos National Laboratory, Laboratory for Laser Energetics, University of Rochester, Univ of Nevada - Reno, University of Nevada, Reno - Physics Department, Jilin University, China, Department of Physics, University of California, Berkeley, Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Advanced Materials Laboratory, National Institute for Materials Science, Department of Physics \& Astronomy, California State University, Long Beach, CA 90840, UC Santa Barbara, Department of Physics and Astronomy, University of California, Riverside, University of California at Merced, Laboratoire de Physique des Plasmas (CNRS/Ecole Polytechnique/UPMC/Universit\'e Paris Sud), Ecole Polytechnique, 91128 Palaiseau, France, University of Nevada, Reno, NV 89557, USA, University of Nevada, Reno, NV 89557 USA, University of Nevada-Reno

  • V.V. Shlyaptseva

    California State University, Dominguez Hills, Univ of California - Irvine, University of Chicago, UC Merced, NINT, Dublin Institute of Technology, Ireland, MIT, NASA/GSFC, CRESST/UMBC \& NASA/GSFC, LLNL, MPI for Plasma Physics, Remeis-Sternwarte/ECAP/FAU, Humboldt State University, University of Nevada Reno, The University of Michigan, University of Nevada, Reno, Lawrence Livermore National Laboratory, Sandia National Laboratories, Los Alamos National Laboratory, Laboratory for Laser Energetics, University of Rochester, Univ of Nevada - Reno, University of Nevada, Reno - Physics Department, Jilin University, China, Department of Physics, University of California, Berkeley, Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Advanced Materials Laboratory, National Institute for Materials Science, Department of Physics \& Astronomy, California State University, Long Beach, CA 90840, UC Santa Barbara, Department of Physics and Astronomy, University of California, Riverside, University of California at Merced, Laboratoire de Physique des Plasmas (CNRS/Ecole Polytechnique/UPMC/Universit\'e Paris Sud), Ecole Polytechnique, 91128 Palaiseau, France, University of Nevada, Reno, NV 89557, USA, University of Nevada, Reno, NV 89557 USA, University of Nevada-Reno

  • V.V. Shlyaptseva

    California State University, Dominguez Hills, Univ of California - Irvine, University of Chicago, UC Merced, NINT, Dublin Institute of Technology, Ireland, MIT, NASA/GSFC, CRESST/UMBC \& NASA/GSFC, LLNL, MPI for Plasma Physics, Remeis-Sternwarte/ECAP/FAU, Humboldt State University, University of Nevada Reno, The University of Michigan, University of Nevada, Reno, Lawrence Livermore National Laboratory, Sandia National Laboratories, Los Alamos National Laboratory, Laboratory for Laser Energetics, University of Rochester, Univ of Nevada - Reno, University of Nevada, Reno - Physics Department, Jilin University, China, Department of Physics, University of California, Berkeley, Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Advanced Materials Laboratory, National Institute for Materials Science, Department of Physics \& Astronomy, California State University, Long Beach, CA 90840, UC Santa Barbara, Department of Physics and Astronomy, University of California, Riverside, University of California at Merced, Laboratoire de Physique des Plasmas (CNRS/Ecole Polytechnique/UPMC/Universit\'e Paris Sud), Ecole Polytechnique, 91128 Palaiseau, France, University of Nevada, Reno, NV 89557, USA, University of Nevada, Reno, NV 89557 USA, University of Nevada-Reno

  • V.V. Shlyaptseva

    California State University, Dominguez Hills, Univ of California - Irvine, University of Chicago, UC Merced, NINT, Dublin Institute of Technology, Ireland, MIT, NASA/GSFC, CRESST/UMBC \& NASA/GSFC, LLNL, MPI for Plasma Physics, Remeis-Sternwarte/ECAP/FAU, Humboldt State University, University of Nevada Reno, The University of Michigan, University of Nevada, Reno, Lawrence Livermore National Laboratory, Sandia National Laboratories, Los Alamos National Laboratory, Laboratory for Laser Energetics, University of Rochester, Univ of Nevada - Reno, University of Nevada, Reno - Physics Department, Jilin University, China, Department of Physics, University of California, Berkeley, Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Advanced Materials Laboratory, National Institute for Materials Science, Department of Physics \& Astronomy, California State University, Long Beach, CA 90840, UC Santa Barbara, Department of Physics and Astronomy, University of California, Riverside, University of California at Merced, Laboratoire de Physique des Plasmas (CNRS/Ecole Polytechnique/UPMC/Universit\'e Paris Sud), Ecole Polytechnique, 91128 Palaiseau, France, University of Nevada, Reno, NV 89557, USA, University of Nevada, Reno, NV 89557 USA, University of Nevada-Reno

  • Susanne Stemmer

    UC Santa Barbara

  • S. James Allen

    UC Santa Barbara