Zero-bias anomaly in the tunneling density of states of graphene

TL;DR

This paper investigates how impurities affect the tunneling density of states in graphene, proposing a method to distinguish scalar potential effects from gauge field effects via angular dependence in STM measurements.

Contribution

It introduces a way to differentiate impurity-induced scalar and gauge fields in graphene using angular dependence of the zero-bias anomaly in tunneling density of states.

Findings

Angular dependence reveals the nature of impurity effects.

Predictions can be tested with scanning tunneling microscopy.

Provides a new diagnostic tool for impurity characterization in graphene.

Abstract

In the vicinity of the Fermi energy, the band structure of graphene is well described by a Dirac equation. Impurities will generally induce both a scalar potential as well as a (fictitious) gauge field acting on the Dirac fermions. We show that the angular dependence of the zero-bias anomaly in the spatially resolved tunneling density of states (TDOS) around a particular impurity allows one to distinguish between these two contributions. Our predictions can be tested in scanning-tunneling-microscopy measurements on graphene.