Lattice relaxation and energy band modulation in twisted bilayer graphene

By N. T. Nam, M. Koshino. 2017

447 citations recorded by the source corpus.

We theoretically study the lattice relaxation in the twisted bilayer graphene (TBG) and its effect on the electronic band structure. We develop an effective continuum theory to describe the lattice relaxation in general TBGs and obtain the optimized structure to minimize the total energy. At small rotation angles $l{2}^{\ensuremath{\circ}}$, in particular, we find that the relaxed lattice drastically reduces the area of the AA stacking region and forms a triangular domain structure with alternating AB and BA stacking regions. We then investigate the effect of the domain formation on the electronic band structure. The most notable change from the nonrelaxed model is that an energy gap of up to 20 meV opens at the superlattice subband edges on the electron and hole sides. We also find that the lattice relaxation significantly enhances the Fermi velocity, which was strongly suppressed in the nonrelaxed model.

Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/2a720de86937aeb4a254a253ecff7d19d36a96c1

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atomic and Molecular Physics, and Optics

In Materials Chemistry

Citations in the corpus

Unconventional superconductivity in magic-angle graphene superlattices (2018, background): “9° to 1°, however, the superlattice gaps at ±ns close and there is no single-particle gap at any energy in the system.(21,56) In this regime, there are Dirac-like bands crossing at ±2ns which might be responsible for the resistance peaks observed in devices with very small twist angles, though possi”
Origin of Magic Angles in Twisted Bilayer Graphene. (2018, background): “In reality, for TBG at tiny twist angles the gap opens and also wAA/wAB is supressed due to lattice relaxation effects [21, 38, 42].”
High-temperature topological superconductivity in twisted double-layer copper oxides (2020, background): “In both cases, the observed behaviour is thought to reflect a subtle interplay between the band structure energetics and topology brought about by the Moiré patterns, electron-electron interactions and disorder [8–17].”
Electronic-structure methods for twisted moiré layers (2020, unknown): “Panel c adapted with permission from reF.(96),”
Maximally Localized Wannier Orbitals and the Extended Hubbard Model for Twisted Bilayer Graphene (2018, methodology): “It was found that the energy gaps isolating the lowest nearly flat bands are also caused by the in-plane distortion [38].”