Interaction effects in graphene in a weak magnetic field

TL;DR

This paper investigates how a weak magnetic field affects electron interactions and symmetry in graphene, revealing anomalous dependencies and new phenomena like the zero-bias anomaly, with implications for experimental observations.

Contribution

It demonstrates the impact of weak magnetic fields on interaction effects and symmetry breaking in graphene, introducing new anomalous behaviors and explaining their microscopic origin.

Findings

Electron-electron interaction lifetime shows anomalous B-dependence.

Zero-bias anomaly emerges at weak B with B^2/ω^2 dependence.

Magnetic field corrections to thermodynamic properties are anomalous.

Abstract

A weak perpendicular magnetic field, $B$, breaks the chiral symmetry of each valley in the electron spectrum of graphene, preserving the overall chiral symmetry in the Brillouin zone. We explore the consequences of this symmetry breaking for the interaction effects in graphene. In particular, we demonstrate that the electron-electron interaction lifetime acquires an anomalous $B$-dependence. Also, the ballistic zero-bias anomaly, $\delta \nu(\omega)$, where $\omega$ is the energy measured from the Fermi level, emerges at a weak $B$ and has the form $\delta\nu(B)\sim B^2/\omega^2$. Temperature dependence of the magnetic-field corrections to the thermodynamic characteristics of graphene is also anomalous. We discuss experimental manifestations of the effects predicted. The microscopic origin of the $B$-field sensitivity is an extra phase acquired by the electron wave-function resulting from the chirality-induced pseudospin precession.