Ellipsometry studies of the optical phonons in hexagonal manganites $R$MnO$_{3}$

ORAL

Abstract

Optical properties of hexagonal multiferroic oxides $R$MnO$_{3}$, where $R=$ Ho, Er, Tm, Yb, and Lu, have been studied in the far-infrared spectral range between 10 and 4000 cm$^{-1}$ and temperatures between 1.5 K and 300 K. An advanced experimental technique of Muller matrix Spectroscopic Ellipsometry was used at the U4IR beamline of the National Synchrotron Light Source, Brookhaven National Lab. Spectra of the optical phonons will be presented in terms of the temperature dependencies of the phonon frequencies, their oscillator strength, anisotropy, and signatures of the spin-phonon interaction at the antiferromagnetic (AFM) phase transition. The spin-phonon interaction reveals itself as a non-Gr\"{u}neisen behavior of several phonon frequencies below $T_{\mathrm{N}}$ (Mn$^{3+})$. A decrease of the ionic radius for $R^{3+}$ ions between Ho$^{3+}$ and Lu$^{3+}$ resulted in a systematic increase of the optical phonon frequency.

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Authors

  • R. Basistyy

    Department of Physics, NJIT, Newark, NJ, USA

  • T.N. Stanislavchuk

    Department of Physics, NJIT, Newark, NJ, USA

  • M. Kotelyanskii

    Rudolph Technologies Inc., NJ, USA

  • N. Lee

    Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers U., NJ, USA

  • X. Wang

    Rutgers Univ, Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers U., NJ, USA

  • S.-W. Cheong

    Rutgers University, Department of Physics, Rutgers University, Rutgers University, NJ, USA, Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA, Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers U., NJ, USA, Rutgers, The State University of New Jersey, Department of Physics and Astronomy, Rutgers University, Rutgers Center for Emergent Materials and Department of Physics and Astronomy, 136 Frelinghuysen Road, Piscataway 08854, NJ, USA

  • G.L. Carr

    National Synchrotron Light Source, Brookhaven National Lab, Upton, NY, USA

  • A.A. Sirenko

    Department of Physics, NJIT, Newark, NJ, USA