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Title: Topological Insulators in Twisted Transition Metal Dichalcogenide Homobilayers

Abstract

We show that moire bands of twisted homobilayers can be topologically nontrivial, and illustrate the tendency by studying valence band states in +/- K valleys of twisted bilayer transition metal dichalcogenides, in particular, bilayer MoTe2. Because of the large spin-orbit splitting at the monolayer valence band maxima, the low energy valence states of the twisted bilayer MoTe2 at the +K (-K) valley can be described using a two-band model with a layer-pseudospin magnetic field Delta(r) that has the moire period. We show that Delta(r) has a topologically nontrivial skyrmion lattice texture in real space, and that the topmost moire valence bands provide a realization of the Kane-Mele quantum spin-Hall model, i. e., the two-dimensional time-reversal-invariant topological insulator. Because the bands narrow at small twist angles, a rich set of broken symmetry insulating states can occur at integer numbers of electrons per moire cell.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science - Office of Basic Energy Sciences - Materials Sciences and Engineering Division; Welch Foundation
OSTI Identifier:
1500107
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 122; Journal Issue: 8; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English

Citation Formats

Wu, Fengcheng, Lovorn, Timothy, Tutuc, Emanuel, Martin, Ivar, and MacDonald, A. H. Topological Insulators in Twisted Transition Metal Dichalcogenide Homobilayers. United States: N. p., 2019. Web. doi:10.1103/PhysRevLett.122.086402.
Wu, Fengcheng, Lovorn, Timothy, Tutuc, Emanuel, Martin, Ivar, & MacDonald, A. H. Topological Insulators in Twisted Transition Metal Dichalcogenide Homobilayers. United States. doi:10.1103/PhysRevLett.122.086402.
Wu, Fengcheng, Lovorn, Timothy, Tutuc, Emanuel, Martin, Ivar, and MacDonald, A. H. Fri . "Topological Insulators in Twisted Transition Metal Dichalcogenide Homobilayers". United States. doi:10.1103/PhysRevLett.122.086402.
@article{osti_1500107,
title = {Topological Insulators in Twisted Transition Metal Dichalcogenide Homobilayers},
author = {Wu, Fengcheng and Lovorn, Timothy and Tutuc, Emanuel and Martin, Ivar and MacDonald, A. H.},
abstractNote = {We show that moire bands of twisted homobilayers can be topologically nontrivial, and illustrate the tendency by studying valence band states in +/- K valleys of twisted bilayer transition metal dichalcogenides, in particular, bilayer MoTe2. Because of the large spin-orbit splitting at the monolayer valence band maxima, the low energy valence states of the twisted bilayer MoTe2 at the +K (-K) valley can be described using a two-band model with a layer-pseudospin magnetic field Delta(r) that has the moire period. We show that Delta(r) has a topologically nontrivial skyrmion lattice texture in real space, and that the topmost moire valence bands provide a realization of the Kane-Mele quantum spin-Hall model, i. e., the two-dimensional time-reversal-invariant topological insulator. Because the bands narrow at small twist angles, a rich set of broken symmetry insulating states can occur at integer numbers of electrons per moire cell.},
doi = {10.1103/PhysRevLett.122.086402},
journal = {Physical Review Letters},
issn = {0031-9007},
number = 8,
volume = 122,
place = {United States},
year = {2019},
month = {2}
}