Comment on “Electron-phonon coupling in two-dimensional silicene and germanene”

M. E. Cifuentes-Quintal, O. de la Peña-Seaman, and R. de Coss
Phys. Rev. B 96, 047401 – Published 25 July 2017

Abstract

In their work, Yan et al. [Phys. Rev. B 88, 121403 (2013)] employing density functional perturbation theory (DFPT) calculations, demonstrate that silicene and germanene show weaker Kohn anomalies in the ΓEg and KA1 phonon modes, compared to graphene. Furthermore, the electron-phonon (e-ph) coupling matrix elements were computed using the frozen-phonon approach. They found that in silicene the average e-ph coupling matrix element square over the Fermi-surface gqν2F is about 50% of those in graphene, but in germanene is weaker and nearly negligible. However, Yan et al. [Phys. Rev. B 88, 121403 (2013)] argue that the smaller Fermi velocity in silicene compensates the reduced gqν2F, leading to phonon linewidths (γqν) slightly larger than those in graphene. In this Comment, we show that the DFPT and the frozen-phonon results of Yan et al. [Phys. Rev. B 88, 121403 (2013)] for silicene are inconsistent. Additionally, we have evaluated the e-ph coupling using direct DFPT calculations, analytical relations, and frozen-phonon calculations, and we found systematically that gqν2F and γqν in silicene are one order of magnitude smaller than in graphene, in contrast to the conclusions of Yan et al. [Phys. Rev. B 88, 121403 (2013)].

  • Figure
  • Received 8 August 2016

DOI:https://doi.org/10.1103/PhysRevB.96.047401

©2017 American Physical Society

Physics Subject Headings (PhySH)

  1. Physical Systems
Condensed Matter, Materials & Applied Physics

Authors & Affiliations

M. E. Cifuentes-Quintal1,*, O. de la Peña-Seaman2, and R. de Coss1

  • 1Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 73, Cordemex, 97310 Mérida, Yucatán, Mexico
  • 2Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apartado Postal J-48, 72570 Puebla, Puebla, Mexico

  • *cifuentes.quintal@gmail.com; miguel.cifuentes@cinvestav.mx

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Original Article

Electron-phonon coupling in two-dimensional silicene and germanene

Jia-An Yan, Ryan Stein, David M. Schaefer, Xiao-Qian Wang, and M. Y. Chou
Phys. Rev. B 88, 121403(R) (2013)

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Issue

Vol. 96, Iss. 4 — 15 July 2017

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