Strong electronic interaction and multiple quantum Hall ferromagnetic phases in trilayer graphene

Area of Science:

• Condensed Matter Physics
• Quantum Mechanics
• Materials Science

Background:

• The Quantum Hall effect is crucial for studying electron interactions in materials.
• Previous trilayer graphene experiments often overlooked strong electronic interactions.
• High-quality graphene samples are necessary to observe interaction-dominated phenomena.

Purpose of the Study:

• To investigate strong electronic interactions in Bernal-stacked trilayer graphene.
• To explore the emergence of quantum Hall ferromagnetism in this system.
• To understand the role of electron-electron interactions in Landau-level gap enhancement.

Main Methods:

• Fabrication of high-mobility trilayer graphene devices (mobility ∼500,000 cm² V⁻¹ s⁻¹).
• Experimental measurements of resistance and Hall effect under varying magnetic fields and filling factors.
• Self-consistent Hartree-Fock calculations to model electronic interactions.

Main Results:

• Evidence of strong electronic interactions and quantum Hall ferromagnetism.
• Observation of all symmetry broken states in the studied trilayer graphene.
• Interaction-enhanced Landau-level gaps, consistent with theoretical calculations.
• Hysteresis and longitudinal resistance spikes indicating quantum Hall ferromagnetic states at low magnetic fields.

Conclusions:

• Bernal-stacked trilayer graphene exhibits significant electronic interactions and quantum Hall ferromagnetism.
• High sample quality is essential for observing these interaction-driven phenomena.
• The findings advance the understanding of correlated electron states in low-dimensional materials.