Static structure factor for graphene in a magnetic field

TL;DR

This paper investigates the static structure factor of graphene in a magnetic field, revealing unique relativistic effects in density correlations due to massless Dirac quasiparticles, with implications for understanding low-energy physics.

Contribution

It demonstrates that the vacuum state in graphene exhibits nonzero density spectral weight and that zero-energy Landau levels are indistinguishable from the vacuum in density response.

Findings

Vacuum state has nonzero density spectral weight.

Density correlations grow with wave vector due to relativistic effects.

Zero-energy Landau levels are indistinguishable from vacuum in density response.

Abstract

A close study is made of the static structure factor for graphene in a magnetic field at integer filling factors nu, with focus on revealing possible signatures of "relativistic" quantum field theory in the low-energy physics of graphene. It is pointed out, in particular, that for graphene even the vacuum state has a nonzero density spectral weight, which, together with the structure factor for all nu, grows significantly with increasing wave vector; such unusual features of density correlations are a "relativistic" effect deriving from massless Dirac quasiparticles in graphene. Remarkably it turns out that the zero-energy Landau levels of electrons or holes, characteristic to graphene, remain indistinguishable in density response from the vacuum state, although they are distinct in Hall conductance.