Phase diagram in strained epitaxial BaTiO$_3$/SrTiO$_3$ superlattices studied by ultraviolet Raman spectroscopy

ORAL

Abstract

Strain effect on phase transitions in nanoscale BaTiO$_3$/SrTiO$_3$ ferroelectric superlattices (SLs) has been studied by ultraviolet (UV) Raman scattering. A series of coherently strained (BaTiO$_3$)$_8$/(SrTiO$_3$)$_4$ SLs have been grown by molecular beam epitaxiy on rare earth scandate (GdScO$_3$, DyScO$_3$, SmScO$_3$, NdScO$_3$) and SrTiO$_3$ substrates. This allowed a systematic strain variation in the SLs. UV Raman data allowed the determination of the ferroelectric phase transition temperature ($T_c$) and indicated the presence of different ferroelectric phases with out-of-plane and in-plane components of polarization in SLs, depending on strain and temperature. Experimental Raman results are supported by first-principles calculations of structural instabilities in BaTiO$_3$/SrTiO$_3$ SLs and thermodynamic phase-field modeling of phase diagrams and ferroelectric polarization as a function of temperature and strain.

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

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Authors

  • Dmitri Tenne

    • Boise State University

  • J.D. Schmidt

    • Boise State University

  • P. Turner

    • Boise State University

  • A. Soukiassian

    • Swiss Federal Institute of Technology (EPFL)

  • D.G. Schlom

    • Materials Science and Engineering, Cornell University
    • Cornell University

  • S. Nakhmanson

    • Argonne National Laboratory
    • Argonne National Lab

  • X.X. Xi

    • Pennsylvania State University
    • Department of Physics, Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802
    • The Pennsylvania State University
    • Department of Physics and Department of Materials Science and Engineering, Penn State University, University Park, PA 16802

  • Y.L. Li

    • Pennstate University
    • Pennsylvania State University

  • Long-Qing Chen

    • Pennstate University
    • Pennsylvania State University

  • M. Bernhagen

    • Institute for Crystal Growth, Berlin, Germany

  • P. Reiche

    • Institute for Crystal Growth, Berlin, Germany

  • R. Uecker

    • Institute for Crystal Growth, Berlin, Germany

  • R. Katiyar

    • University of Puerto Rico