First-principles calculation and experimental investigation of lattice dynamics in the rare-earth pyrochlores R2Ti2O7 (R=Tb,Dy,Ho)

M. Ruminy, M. Núñez Valdez, B. Wehinger, A. Bosak, D. T. Adroja, U. Stuhr, K. Iida, K. Kamazawa, E. Pomjakushina, D. Prabakharan, M. K. Haas, L. Bovo, D. Sheptyakov, A. Cervellino, R. J. Cava, M. Kenzelmann, N. A. Spaldin, and T. Fennell
Phys. Rev. B 93, 214308 – Published 29 June 2016

Abstract

We present a model of the lattice dynamics of the rare-earth titanate pyrochlores R2Ti2O7 (R=Tb,Dy,Ho), which are important materials in the study of frustrated magnetism. The phonon modes are obtained by density functional calculations, and these predictions are verified by comparison with scattering experiments. Single crystal inelastic neutron scattering is used to measure acoustic phonons along high symmetry directions for R=Tb, Ho; single crystal inelastic x-ray scattering is used to measure numerous optical modes throughout the Brillouin zone for R=Ho; and powder inelastic neutron scattering is used to estimate the phonon density of states for R=Tb, Dy, Ho. Good agreement between the calculations and all measurements is obtained, allowing confident assignment of the energies and symmetries of the phonons in these materials under ambient conditions. Knowledge of the phonon spectrum is important for understanding spin-lattice interactions, and can be expected to be transferred readily to other members of the series to guide the search for unconventional magnetic excitations.

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  • Received 14 April 2016
  • Revised 19 May 2016

DOI:https://doi.org/10.1103/PhysRevB.93.214308

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

M. Ruminy1,*, M. Núñez Valdez2,†, B. Wehinger1,3, A. Bosak4, D. T. Adroja5,6, U. Stuhr1, K. Iida7, K. Kamazawa7, E. Pomjakushina8, D. Prabakharan9, M. K. Haas10,‡, L. Bovo11, D. Sheptyakov1, A. Cervellino12, R. J. Cava10, M. Kenzelmann8, N. A. Spaldin2, and T. Fennell1,§

  • 1Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
  • 2Materials Theory, ETH Zurich, Wolfgang-Pauli-Straße 27, 8093 Zurich, Switzerland
  • 3Department of Quantum Matter Physics, University of Geneva, 24, Quai Ernest-Ansermet, 1211, Geneva 4, Switzerland
  • 4ESRF–The European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
  • 5ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, United Kingdom
  • 6Highly Correlated Electron Group, Physics Department, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa
  • 7Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
  • 8Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
  • 9Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, United Kingdom
  • 10Department of Chemistry, Princeton University, Princeton, New Jersey 08540, USA
  • 11London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WC1H 0AH, United Kingdom
  • 12Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland

  • *martin.ruminy@gmx.de
  • Present address: Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia.
  • Present address: Air Products and Chemicals Inc., Allentown, PA 18195, USA.
  • §tom.fennell@psi.ch

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Issue

Vol. 93, Iss. 21 — 1 June 2016

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