2 research outputs found
Strain impacts on commensurate bilayer graphene superlattices: distorted trigonal warping, emergence of bandgap and direct-indirect bandgap transition
Due to low dimensionality, the controlled stacking of the graphene films and
their electronic properties are susceptible to environmental changes including
strain. The strain-induced modification of the electronic properties such as
the emergence and modulation of bandgaps crucially depends on the stacking of
the graphene films. However, to date, only the impact of strain on electronic
properties of Bernal and AA-stacked bilayer graphene has been extensively
investigated in theoretical studies. Exploiting density functional theory and
tight-binding calculation, we investigate the impacts of in-plane strain on two
different class of commensurate twisted bilayer graphene (TBG) which are
even/odd under sublattice exchange (SE) parity. We find that the SE odd TBG
remains gapless whereas the bandgap increases for the SE even TBG when applying
equibiaxial tensile strain. Moreover, we observe that for extremely large mixed
strains both investigated TBG superstructures demonstrate direct-indirect
bandgap transition.Comment: 8 pages, 8 figure
Impacts of in-plane strain on commensurate graphene/hexagonal boron nitride superlattices
Due to atomically thin structure, graphene/hexagonal boron nitride (G/hBN)
heterostructures are intensively sensitive to the external mechanical forces
and deformations being applied to their lattice structure. In particular,
strain can lead to the modification of the electronic properties of G/hBN.
Furthermore, moir\'e structures driven by misalignment of graphene and hBN
layers introduce new features to the electronic behavior of G/hBN. Utilizing
{\it ab initio} calculation, we study the strain-induced modification of the
electronic properties of diverse stacking faults of G/hBN when applying
in-plane strain on both layers, simultaneously. We observe that the interplay
of few percent magnitude in-plane strain and moir\'e pattern in the
experimentally applicable systems leads to considerable valley drifts, band gap
modulation and enhancement of the substrate-induced Fermi velocity
renormalization. Furthermore, we find that regardless of the strain alignment,
the zigzag direction becomes more efficient for electronic transport, when
applying in-plane non-equibiaxial strains.Comment: 8 pages and 6 figure