Fine structure of the lowest Landau level in suspended trilayer graphene

TL;DR

This study investigates the detailed electronic structure of the lowest Landau level in suspended ABC-stacked trilayer graphene, revealing a complete degeneracy splitting and a hierarchy of quantum Hall states driven by exchange interactions.

Contribution

It provides a detailed experimental analysis of Landau level splitting and quantum Hall hierarchy in ABC-stacked trilayer graphene, highlighting exchange effects and layer asymmetry influences.

Findings

Complete splitting of the twelve-fold degenerated lowest Landau level.

Hierarchy of quantum Hall states: ν=6, 4, 0, 3, 1, 2, 5.

Observation of a ν=4 state likely caused by layer asymmetry.

Abstract

Magneto-transport experiments on ABC-stacked suspended trilayer graphene reveal a complete splitting of the twelve-fold degenerated lowest Landau level, and, in particular, the opening of an exchange-driven gap at the charge neutrality point. A quantitative analysis of distinctness of the quantum Hall plateaus as a function of field yields a hierarchy of the filling factors: \nu=6, 4, and 0 are the most pronounced, followed by \nu=3, and finally \nu=1, 2 and 5. Apart from the appearance of a \nu=4 state, which is probably caused by a layer asymmetry, this sequence is in agreement with Hund's rules for ABC-stacked trilayer graphene.