Pseudo-zero-mode Landau levels and collective excitations in bilayer graphene

TL;DR

This paper investigates the properties of pseudo-zero-mode Landau levels in bilayer graphene under magnetic and electric fields, revealing controllable charge and collective excitation phenomena with potential experimental implications.

Contribution

It introduces the detailed behavior of pseudo-zero-mode Landau levels, including their splitting, charge carrier properties, and collective excitations influenced by Coulomb interactions and external fields.

Findings

Charge carriers with electric moments due to orbital level mixing.

Field-induced level splitting and quantum Hall effects.

Rich spectra of collective excitations accessible by microwave experiments.

Abstract

Bilayer graphene in a magnetic field supports eight zero-energy Landau levels, which, as a tunable band gap develops, split into two nearly-degenerate quartets separated by the band gap. A close look is made into the properties of such an isolated quartet of pseudo-zero-mode levels at half filling in the presence of an in-plane electric field and the Coulomb interaction, with focus on revealing further controllable features in bilayer graphene. The half-filled pseudo-zero-mode levels support, via orbital level mixing, charge carriers with nonzero electric moment, which would lead to field-induced level splitting and the current-induced quantum Hall effect. It is shown that the Coulomb interaction enhances the effect of the in-plane field and their interplay leads to rich spectra of collective excitations, pseudospin waves, accessible by microwave experiments; also a duality in the excitation spectra is revealed.