Effective Hamiltonian of Strained Graphene

TL;DR

This paper derives an effective Hamiltonian for strained graphene, accounting for symmetry properties and substrate effects, enabling analysis of strain-induced phenomena like bandgap opening and pseudo-magnetic fields.

Contribution

The paper presents a new effective Hamiltonian model for non-uniform strain in graphene, including substrate effects and symmetry breaking, which aligns with first-principles calculations.

Findings

Hamiltonian reproduces first-principles spectra up to 10% strain

Out-of-plane optical strain opens a bandgap in graphene

Model facilitates analysis of strain-induced electron-phonon interactions

Abstract

Based on the symmetry properties of graphene lattice, we derive the effective Hamiltonian of graphene under spatially non-uniform acoustic and optical strains. We show that with the proper selection of the parameters, the obtained Hamiltonian reproduces the results of first-principles spectrum calculations for acoustic strain up to 10%. The results are generalized for the case of graphene with broken plane reflection symmetry, which corresponds, for example, to the case of graphene placed at a substrate. Here, essential modifications to the Hamiltonian give rise, in particular, to the gap opening in the spectrum in the presence of the out of plane component of optical strain, which is shown to be due to the lifting of the sublattice symmetry. The developed effective Hamiltonian can be used as a convenient tool for analysis of a variety of strain-related effects, including electron-phonon interaction or pseudo-magnetic fields induced by the non-uniform strain.