Spontaneous Gully-Polarized Quantum Hall States in ABA Trilayer Graphene

Bernal-stacked multilayer graphene is a versatileplatform to explore quantum transport phenomena and interactionphysics due to its exceptional tunability via electrostatic gating. Forinstance, upon applying a perpendicular electricfield, its bandstructure exhibits several off-center Dirac points (so-called Diracgullies) in each valley. Here, the formation of Dirac gullies and theinteraction-induced breakdown of gully coherence is explored viamagnetotransport measurements in high-quality Bernal-stacked(ABA) trilayer graphene. At zero magneticfield, multiple Lifshitztransitions indicating the formation of Dirac gullies are identified.In the quantum Hall regime, the emergence of Dirac gullies isevident as an increase in Landau level degeneracy. When tuningboth electric and magneticfields, electron-electron interactionscan be controllably enhanced until, beyond critical electric and magneticfields, the gully degeneracy is eventually lifted. The arisingcorrelated ground state is consistent with a previously predicted nematic phase that spontaneously breaks the rotational gully symmetry

Automated summary

In this study, the formation of Dirac gullies and the interaction-induced breakdown of gully coherence were explored through magnetotransport measurements in high-quality Bernal-stacked trilayer graphene. The emergence of Dirac gullies in the quantum Hall regime and the control of electron-electron interactions through electric and magnetic fields were observed, leading to the lifting of gully degeneracy and the formation of a correlated ground state.