Probing IrTe2 crystal symmetry by polarized Raman scattering

N. Lazarević, E. S. Bozin, M. Šćepanović, M. Opačić, Hechang Lei (雷和畅), C. Petrovic, and Z. V. Popović
Phys. Rev. B 89, 224301 – Published 16 June 2014

Abstract

Polarized Raman scattering measurements on IrTe2 single crystals carried out over the 15–640 K temperature range, and across the structural phase transition, reveal different insights regarding the crystal symmetry. In the high temperature regime three Raman active modes are observed at all of the studied temperatures above the structural phase transition, rather than two as predicted by the factor group analysis for the assumed P3¯m1 symmetry. This indicates that the actual symmetry of the high temperature phase is lower than previously thought. The observation of an additional Eg mode at high temperature can be explained by doubling of the original trigonal unit cell along the c axis and within the P3¯c1 symmetry. In the low temperature regime (below 245 K) the other Raman modes appear as a consequence of the symmetry lowering phase transition and the corresponding increase of the primitive cell. All of the modes observed below the phase transition temperature can be assigned within the monoclinic crystal symmetry. The temperature dependence of the Raman active phonons in both phases is mainly driven by anharmonicity effects. The results call for reconsideration of the crystallographic phases of IrTe2.

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  • Received 7 April 2014
  • Revised 26 May 2014

DOI:https://doi.org/10.1103/PhysRevB.89.224301

©2014 American Physical Society

Authors & Affiliations

N. Lazarević1, E. S. Bozin2, M. Šćepanović1, M. Opačić1, Hechang Lei (雷和畅)2, C. Petrovic2, and Z. V. Popović1

  • 1Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
  • 2Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973-5000, USA

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Vol. 89, Iss. 22 — 1 June 2014

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