Optical properties of BiTeBr and BiTeCl

Ana Akrap, Jérémie Teyssier, Arnaud Magrez, Philippe Bugnon, Helmuth Berger, Alexey B. Kuzmenko, and Dirk van der Marel
Phys. Rev. B 90, 035201 – Published 2 July 2014

Abstract

We present a comparative study of the optical properties—reflectance, transmission, and optical conductivity—and Raman spectra of two layered bismuth-tellurohalides BiTeBr and BiTeCl at 300 and 5 K, for light polarized in the a-b planes. Despite different space groups, the optical properties of the two compounds are very similar. Both materials are doped semiconductors, with the absorption edge above the optical gap which is lower in BiTeBr (0.62 eV) than in BiTeCl (0.77 eV). The same Rashba splitting is observed in the two materials. A non-Drude free carrier contribution in the optical conductivity, as well as three Raman and two infrared phonon modes, are observed in each compound. There is a dramatic difference in the highest infrared phonon intensity for the two compounds, and a difference in the doping levels. Aspects of the strong electron-phonon interaction are identified. Several interband transitions are assigned, among them the low-lying absorption β which has the same value 0.25 eV in both compounds, and is caused by the Rashba spin splitting of the conduction band. An additional weak transition is found in BiTeCl, caused by the lower crystal symmetry.

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  • Received 8 April 2014
  • Revised 19 June 2014

DOI:https://doi.org/10.1103/PhysRevB.90.035201

©2014 American Physical Society

Authors & Affiliations

Ana Akrap1,*, Jérémie Teyssier1, Arnaud Magrez2, Philippe Bugnon2, Helmuth Berger2, Alexey B. Kuzmenko1, and Dirk van der Marel1

  • 1DPMC, University of Geneva, CH-1211 Geneva 4, Switzerland
  • 2Crystal Growth Facility, Institut de Physique de la Matière Condensée, École Polytechnique Fédérale de Lausanne, Switzerland

  • *ana.akrap@unige.ch

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Vol. 90, Iss. 3 — 15 July 2014

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