Charge 2e skyrmions in bilayer graphene

TL;DR

This paper demonstrates that in bilayer graphene's quantum Hall states, electric charge is carried by charge 2e skyrmions at even filling factors, revealing a rare charge binding phenomenon with potential experimental signatures.

Contribution

It introduces the concept of charge 2e skyrmions in bilayer graphene and analyzes their properties and experimental signatures, a novel finding in systems with purely repulsive interactions.

Findings

Charge 2e skyrmions exist at even filling factors.

Skyrmion energy and size depend on Zeeman interaction.

Potential detection via scanning tunneling microscopy.

Abstract

Quantum Hall states that result from interaction induced lifting of the eight-fold degeneracy of the zeroth Landau level in bilayer graphene are considered. We show that at even filling factors electric charge is injected into the system in the form of charge $2e$ skyrmions. This is a rare example of binding of charges in a system with purely repulsive interactions. We calculate the skyrmion energy and size as a function of the Zeeman interaction, and discuss signatures of the charge $2e$ skyrmions in the scanning tunneling microscopy experiments.