Group theory analysis of phonons in two-dimensional transition metal dichalcogenides
Name
PhysRevB.90.115438.pdf
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889.07 KB
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Checksum (MD5)
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Author(s)
Ribeiro-Soares, J.
Almeida, R. M.
Barros, Eduardo B.
Araujo, Paulo Antonio Trinidade
Jorio, A.
Dresselhaus, Mildred
Cancado, L. G.
Date Issued
September 2014
Journal
Physical Review B
Publisher
American Physical Society
Citation
Ribeiro-Soares, J., et al. "Group theory analysis of phonons in two-dimensional transition metal dichalcogenides." Phys. Rev. B 90, 115438 (September 2014). © 2014 American Physical Society
Version
Final published version
Abstract
Transition metal dichalcogenides (TMDCs) have emerged as a new two-dimensional material's field since the monolayer and few-layer limits show different properties when compared to each other and to their respective bulk materials. For example, in some cases when the bulk material is exfoliated down to a monolayer, an indirect-to-direct band gap in the visible range is observed. The number of layers N (N even or odd) drives changes in space-group symmetry that are reflected in the optical properties. The understanding of the space-group symmetry as a function of the number of layers is therefore important for the correct interpretation of the experimental data. Here we present a thorough group theory study of the symmetry aspects relevant to optical and spectroscopic analysis, for the most common polytypes of TMDCs, i.e., 2Ha, 2Hc and 1T, as a function of the number of layers. Real space symmetries, the group of the wave vectors, the relevance of inversion symmetry, irreducible representations of the vibrational modes, optical activity, and Raman tensors are discussed.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Massachusetts Institute of Technology. Department of Physics
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1103/PhysRevB.90.115438
