Homoepitaxial off-stoichiometric SrTiO$_{3}$ films studied by ultraviolet Raman spectroscopy

ORAL

Abstract

Homoepitaxial Sr$_{1+x}$TiO$_{3+\delta }$ films with -0.2$<$x$<$0.25 grown by reactive molecular-beam epitaxy on SrTiO$_{3}$ (001) substrates have been studied by ultraviolet Raman spectroscopy. Off-stoichiometry for strontium-deficient compositions leads to the appearance of strong first-order Raman scattering at low temperatures, which decreases with increasing temperature and disappears at about 350 K. This indicates the appearance of spontaneous polarization with $T_{c}$ above room temperature. Strontium-rich samples also show strong first-order Raman signal, but the peaks are significantly broader and exhibit a less pronounced temperature dependence, indicating a stronger contribution of the disorder-activated mechanism in Raman scattering.

*Supported in part by NSF, DOE, and Research Corporation for Science Advancement.

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Authors

  • Andrew Farrar

    • Boise State University, Physics Dept.

  • D.A. Tenne

    • Boise State University, Physics Dept.

  • Charles Brooks

    • The Pennsylvania State University
    • Cornell University, Dept. of Materials Science and Engineering
    • Department of Materials Science and Engineering, Pennsylvania State University

  • L. Fitting Kourkoutis

    • Cornell University
    • Cornell University, School of Applied and Engineering Physics

  • T. Heeg

    • Cornell University, Dept. of Materials Science and Engineering

  • J. Schubert

    • Institute of Bio- and Nanosystems, Forschungszentrum J\&#034;ulich, Germany

  • D.A. Muller

    • Cornell University, School of Applied and Engineering Physics

  • D.G. Schlom

    • Cornell University, Dept. of Materials Science and Engineering