Chemical trends in homo- and hetero- twisted bilayer transition metal dichalcogenides from ab-initio tight-binding

Recently, it has been shown that small-angle twisted bilayer transition metal dichalcogenides (tBL-TMDs) may exhibit rich phase diagrams as function of carrier density and temperature [1-5]. The emergence of competing electronic phases, including correlated insulating and superconducting phases, is attributed mainly to strong electron-electron interactions in the localized states associated with the flat bands near the Fermi level [6].
At small twist angles, the large size of the moiré cells makes first-principles calculations of the atomic and electronic structure challenging. To overcome this obstacle, we employ a multi-scale approach, in which classical force fields are used to find equilibrium atomic structures [8] and tight-binding calculations are carried out on the relaxed structures to determine electronic band structures [7]. We present results for the band structures of different homo- and hetero-tBL-TMDs and discuss the dependence on twist angle and chemistry of the constituent monolayers.
Refs.
[1] Nat. Mat. 19, pages 861–866 (2020)
[2] Nat. Mat. 19, pages 824–826 (2020)
[3] arXiv.2006.05615 (2020)
[4] Nat. Comm. 11, 2153 (2020)
[5] arXiv:2007.12068 (2020)
[6] Phys. Rev. Lett. 121, 266401 (2018)
[7] Phys. Rev. B 92, 205108 (2015)
[8] J. Phys. Chem. C, 123, 15, 9770–9778 (2019)