Tight-binding approach to strain and curvature in monolayer transition-metal dichalcogenides

Alexander J. Pearce, Eros Mariani, and Guido Burkard
Phys. Rev. B 94, 155416 – Published 12 October 2016

Abstract

We present a model of the electronic properties of monolayer transition-metal dichalcogenides based on a tight-binding approach which includes the effects of strain and curvature of the crystal lattice. Mechanical deformations of the lattice offer a powerful route for tuning the electronic structure of the transition-metal dichalcogenides, as changes to bond lengths lead directly to corrections in the electronic Hamiltonian while curvature of the crystal lattice mixes the orbital structure of the electronic Bloch bands. We first present an effective low-energy Hamiltonian describing the electronic properties near the K point in the Brillouin zone, then present the corrections to this Hamiltonian due to arbitrary mechanical deformations and curvature in a way which treats both effects on an equal footing. This analysis finds that local area variations of the lattice allow for tuning of the band gap and effective masses, while the application of uniaxial strain decreases the magnitude of the direct band gap at the K point. Additionally, strain induced bond length modifications create a fictitious gauge field with a coupling strength that is smaller than that seen in related materials like graphene. We also find that curvature of the lattice leads to the appearance of both an effective in-plane magnetic field which couples to spin degrees of freedom and a Rashba-like spin-orbit coupling due to broken mirror inversion symmetry.

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  • Received 19 November 2015
  • Revised 19 July 2016

DOI:https://doi.org/10.1103/PhysRevB.94.155416

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Alexander J. Pearce1, Eros Mariani2, and Guido Burkard1

  • 1Department of Physics, University of Konstanz, D-78464 Konstanz, Germany
  • 2School of Physics, University of Exeter, Stocker Rd., EX4 4QL Exeter, United Kingdom

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Issue

Vol. 94, Iss. 15 — 15 October 2016

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