Band structures and topological properties of twisted bilayer MoTe₂ and WSe₂

Abstract

We calculate the electronic band structures and topological properties of twisted homobilayer transition metal dichalcogenides(t-TMDs), in particular, bilayer MoTe2 and WSe2 based on a low-energy effective continuum model. We systematically show how the twist angle, vertical electric field and pressure modify the band structures of t-TMDs, often accompanied by topological transitions.We find the variation of topological transitions mainly take place in a limited range of parameters. The electric field can efficiently tune the energy of the topmost second valence band to motify the Chern numbers of the topmost three valance bands. The topological property of the topmost first valance band can be modified by electric field and pressure, but doesn’t depend on twist angle. We show the band gap between the topmost second and third valance bands that both change from non-trivial to trivial closes at κ − -point of the moiré Brillouin zone.

Strong manipulation of the valley splitting upon twisting and gating in MoSe2/CrI3 and WSe2/CrI3Zollner1, Junior2, Fabian3 2023Phys. Rev. B16140View full textAdd to dashboardCite

“…The most prominent examples are twisted bilayer and trilayer graphene, exhibiting magnetism and superconductivity due to strong correlations . Other platforms for correlated physics are offered by twisted TMDCs [100][101][102] and twisted CrI 3 mono-and bilayers [103,104]. Regarding proximity effects, a recent study shows the sensitivity of the spin polarization, magnetic anisotropy, and Dzyaloshinskii-Moriya interaction on the twist angle in graphene/2H-VSeTe heterostructures [105].…”

Flat bands and topological properties of twisted bilayer WSe2 under external stimuli

“…The reason why we choose 1 °is that the bandwidth of the first flat band increases with the increase of twist angle [54]. In order to obtain an extremely narrow bandwidth, we choose 1 °angle here.…”

Effects of strain on the flat band in twisted bilayer graphene

“…[20][21][22][23] These novel quantum states originate from the formation of flat electronic bands near a magic twisted angle (∼ 1 ∘ ) under the influence of the moiré superlattice. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] Such flat bands exhibit a sensitive dependence on small lattice deformations [24,38] that are induced by lattice relaxation or strain. On the other hand, strain is an effective tool for engineering the flat bands [24,39] and thus helps us understand the various exotic quantum states in TBG.…”

“…Previous experimental [8] and theoretical works [24,36,[39][40][41] have shown that applying a heterostrain (relative strains between layers) in a two-layer structure can significantly modify the band structures and electronic phases. Due to the interaction between substrate and graphene in the preparation process, various strains are prevalent in actual TBG samples.…”