Electronic spectrum and optical properties of Y-shaped Kekule-patterned graphene: Band nesting resonance as an optical signature

TL;DR

This paper studies how a Y-shaped Kekule distortion in graphene affects its electronic and optical properties, revealing a robust band nesting resonance that can serve as an optical signature even at room temperature.

Contribution

It provides an analytical framework for understanding the optical response of Kekule-distorted graphene and identifies a distinctive, temperature-robust optical resonance signature.

Findings

Y-shaped Kekule distortion induces a large optical response.

Band nesting resonance is robust against temperature increases.

Optical signature can be detected at room temperature.

Abstract

Employing tight-binding model we investigate the effects of a uniform Y-shaped Kekule lattice distortion on the electronic spectrum and optical conductivity of graphene. We derive a low-energy effective Hamiltonian which is found to be in excellent agreement with one calculated from a diagonalization of the full tight-binding Hamiltonian. Then using the low-energy Hamiltonian and Kubo formula we obtain an analytical expression for the real part of the optical conductivity used to explore the effects of chemical potential, temperature and on-site and hopping energy deviations in details. In particular we find that Y-shaped Kekue-patterned graphene at finite chemical potential displays a large optical response called band nesting resonance. This effect is shown to be robust against increasing temperature, facilitating its detection as an optical signature for the Y-shaped Kekule distortion even at room temperature.