Inter-subband Landau level couplings induced by in-plane magnetic fields in trilayer graphene

TL;DR

This study reveals how in-plane magnetic fields induce couplings between Landau levels in trilayer graphene, leading to observable quantum Hall effects and level crossings, explained through a developed tight-binding model.

Contribution

The paper introduces a theoretical model explaining inter-subband Landau level couplings induced by in-plane magnetic fields in trilayer graphene.

Findings

Observation of broken-symmetry quantum Hall effects.

Identification of Landau level crossings at specific magnetic field orientations.

Development of a tight-binding model explaining the couplings.

Abstract

We observed broken-symmetry quantum Hall effects and level crossings between spin- and valley- resolved Landau levels (LLs) in Bernal stacked trilayer graphene. When the magnetic field was tilted with respect to sample normal from $0^{\circ}$ to $66^\circ$, the LL crossings formed at intersections of zeroth and second LLs from monolayer-graphene-like and bilayer-graphene-like subbands, respectively, exhibited a sequence of transitions. The results indicate the LLs from different subbands are coupled by in-plane magnetic fields ($B_{\parallel}$), which was explained by developing the tight-binding model Hamiltonian of trilayer graphene under $B_{\parallel}$.