Large-gap topological insulators in functionalized ordered double transition metal carbide MXenes

Zhi-Quan Huang, Mei-Ling Xu, Gennevieve Macam, Chia-Hsiu Hsu, and Feng-Chuan Chuang
Phys. Rev. B 102, 075306 – Published 14 August 2020
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Abstract

Two-dimensional MXenes continue to receive much research attention owing to their versatility and predicted topological phase, which are yet to be fully explored. Here, we conduct a rigorous search on M2MC2 (M=V, Nb, or Ta;M=Ti, Zr, or Hf) with various surface terminations, X2 (X=F, Cl, Br, I, O, H, or OH), using first-principles calculations. The majority of the systems exhibit the topological phase with semimetallic band structures. Most importantly, fluorinated MXenes, M2MC2F2, are topological insulators. They possess sizable nontrivial band gaps from 34 to 318 meV using Heyd-Scuseria-Ernzerhof (HSE) hybrid functional calculations which are within the range capable of realizing quantum spin-Hall effects even at room temperature. Furthermore, the d orbitals of M and M atoms mostly contribute to the spin-orbit coupling-induced band gaps. Selecting V2TiC2F2 as an exemplar, we demonstrate the presence of edge states, verifying the calculated Z2 invariant, and reveal its robustness against tensile strain. Finally, we propose SiC(0001) as a candidate substrate for material realization as it can preserve the nontrivial band topology.

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  • Received 11 July 2019
  • Accepted 27 July 2020

DOI:https://doi.org/10.1103/PhysRevB.102.075306

©2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Zhi-Quan Huang1,*, Mei-Ling Xu1,*, Gennevieve Macam1,*, Chia-Hsiu Hsu1,*, and Feng-Chuan Chuang1,2,3,†

  • 1Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
  • 2Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
  • 3Physics Division, National Center for Theoretical Sciences, Hsinchu 30013, Taiwan

  • *These authors contributed equally to this work.
  • fchuang@mail.nsysu.edu.tw

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Issue

Vol. 102, Iss. 7 — 15 August 2020

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