paper

Effective continuum model of twisted bilayer GeSe and origin of emerging one-dimensional mode

arXiv:2107.07149 · doi:10.1103/PhysRevB.104.125427

Abstract

The electric structure of twisted bilayer GeSe, which shows a rectangular moiré pattern, is analyzed using a type effective continuum model. The effective model is constructed on the basis of the the local approximation method, where the local lattice structure of a twisted bilayer system is approximated by its untwisted bilayer with parallel displacement, and the required parameters are fixed with the help of the first-principles method. By inspecting the twist angle dependence of the physical properties, we reveal a relation between the effective potential under moiré pattern and the alignment of the Ge atoms, and also the resultant one-dimensional flat band, where the band is flattened stronger in a specific direction than the perpendicular direction. Due to the relatively large effective mass of the original monolayers, the flat band with its band width as small as a few meV appear in a relatively large angle. This gives us an opportunity to explore the dimensional crossover in the twisted bilayer platform.

11 pages, 6 figures

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