2018/07/31 by Fengcheng Wu, Timothy Lovorn, Emanuel Tutuc +2 · 2 citations
Physics and Astronomy · #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevlett.122.086402
published as Phys. Rev. Lett. 122, 086402 (2019) · 5+5 pages, 4+4 figures. Title has been modified. Accepted by Physical Review Letters on February 7, 2019
arxiv created 2019/02/11 · arxiv updated 2019/03/06
We show that moiré 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 +K (-K) valley can be described using a two-band model with a layer-pseudospin magnetic field \boldsymbolΔ(\boldsymbolr) that has the moiré period. We show that \boldsymbolΔ(\boldsymbolr) has a topologically non-trivial skyrmion lattice texture in real space, and that the topmost moiré 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 moiré cell.