Charge 2e skyrmions in bilayer graphene

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Graphene Physics

Background:

• Bilayer graphene exhibits complex quantum Hall states due to interactions lifting Landau level degeneracy.
• The zeroth Landau level in bilayer graphene possesses an eightfold degeneracy that is sensitive to interaction effects.

Purpose of the Study:

• To investigate the nature of charge carriers injected into bilayer graphene at even filling factors within specific quantum Hall states.
• To analyze the formation and properties of emergent quasiparticles resulting from interaction-induced phenomena.
• To explore the possibility of charge binding in systems dominated by repulsive interactions.

Main Methods:

• Theoretical analysis of quantum Hall states in bilayer graphene.
• Calculation of Skyrmion energy and size as a function of effective Zeeman interaction.
• Modeling of charge 2e Skyrmion formation at even filling factors.

Main Results:

• Electric charge is injected as charge 2e Skyrmions at even filling factors in the considered quantum Hall states.
• Demonstration of charge binding occurring in a system with predominantly repulsive interactions.
• Quantification of Skyrmion energy and size dependence on Zeeman interaction.

Conclusions:

• The study identifies charge 2e Skyrmions as the injected charge carriers in specific bilayer graphene quantum Hall states.
• The findings present a rare instance of charge binding driven by interactions in a repulsive system.
• The calculated Skyrmion properties provide a basis for experimental verification using scanning probe techniques.