Vacuum polarization in graphene with a topological defect

TL;DR

This paper investigates how topological defects in graphene, modeled as nanocones with pseudomagnetic vortices, affect the ground state electronic properties, revealing defect-induced condensates and currents.

Contribution

It introduces a continuum model using self-adjoint extensions to analyze electronic states in graphene nanocones with topological defects, highlighting defect-dependent ground state phenomena.

Findings

Ground state condensate and currents are induced by topological defects.

The electronic properties depend on the cone's deficit angle and boundary conditions.

The model provides a framework for understanding defect effects in graphene nanostructures.

Abstract

The influence of a topological defect in graphene on the ground state of electronic quasiparticle excitations is studied in the framework of the long-wavelength continuum model originating in the tight-binding approximation for the nearest neighbour interaction in the graphitic lattice. A topological defect that rolls up a graphitic sheet into a nanocone is represented by a pointlike pseudomagnetic vortex with a flux which is related to the deficit angle of the cone. The method of self-adjoint extensions is employed to define the set of physically acceptable boundary conditions at the apex of the nanocone. The electronic system on a graphitic nanocone is found to acquire the ground state condensate and current of special type, and we determine the dependence of these quantities on the deficit angle of the nanocone, continuous parameter of the boundary condition at the apex, and the distance from the apex.