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

TL;DR

This study demonstrates strong electronic interactions and quantum Hall ferromagnetic phases in high-mobility ABA trilayer graphene, revealing symmetry breaking and interaction-enhanced Landau Level gaps through experimental and theoretical analysis.

Contribution

It provides the first evidence of interaction-driven quantum Hall ferromagnetism in ABA trilayer graphene with high mobility, supported by self-consistent Hartree-Fock calculations.

Findings

Observation of all symmetry broken states.

Enhanced Landau Level gaps due to interactions.

Detection of hysteresis and resistance spikes indicating QHF states.

Abstract

There is an increasing interest in the electronic properties of few layer graphene as it offers a platform to study electronic interactions because the dispersion of bands can be tuned with number and stacking of layers in combination with electric field. However, electronic interaction becomes important only in very clean devices and so far the trilayer graphene experiments are understood within non-interacting electron picture. Here, we report evidence of strong electronic interactions and quantum Hall ferromagnetism (QHF) seen in ABA trilayer graphene (ABA-TLG). Due to high mobility $\sim$500,000 cm$^2$V$^{-1}$s$^{-1}$ in our device compared to previous studies, we find all symmetry broken states and that Landau Level (LL) gaps are enhanced by interactions; an aspect explained by our self-consistent Hartree-Fock (H-F) calculations. Moreover, we observe hysteresis as a function of filling factor ($\nu$) and spikes in the longitudinal resistance which, together, signal the formation of QHF states at low magnetic field.