Semimetalic graphene in a modulated electric potential

TL;DR

This paper studies how a modulated electric potential alters graphene's electronic structure, revealing transitions from semiconducting to semimetallic states and creating complex Fermi-momentum states with distinctive density of states features.

Contribution

It demonstrates that a modulated electric potential can induce semimetallic behavior in graphene and significantly modify its electronic properties, a novel insight into electric field effects on 2D materials.

Findings

Electric potential modulates energy dispersions and induces band-edge states.

Transition from semiconducting to semimetallic behavior depends on field strength.

Density of states at Fermi level becomes finite with prominent peaks.

Abstract

The $\pi$-electronic structure of graphene in the presence of a modulated electric potential is investigated by the tight-binding model. The low-energy electronic properties are strongly affected by the period and field strength. Such a field could modify the energy dispersions, destroy state degeneracy, and induce band-edge states. It should be noted that a modulated electric potential could make semiconducting graphene semimetallic, and that the onset period of such a transition relies on the field strength. There exist infinite Fermi-momentum states in sharply contrast with two crossing points (Dirac points) for graphene without external fields. The finite density of states (DOS) at the Fermi level means that there are free carriers, and, at the same time, the low DOS spectrum exhibits many prominent peaks, mainly owing to the band-edge states.