Field induced quantum-Hall ferromagnetism in suspended bilayer graphene

TL;DR

This study demonstrates field-induced quantum-Hall ferromagnetism in suspended bilayer graphene, revealing a magnetic field-driven transition to an insulating ferromagnetic phase at the charge neutrality point.

Contribution

It provides experimental evidence of a field-induced ferromagnetic insulating phase in bilayer graphene, highlighting symmetry breaking and Landau level lifting.

Findings

Observation of a field-induced gap at charge neutrality

Complete lifting of the eight-fold degenerated Landau level

Identification of a ferromagnetic nature of the insulating phase

Abstract

We have measured the magneto-resistance of freely suspended high-mobility bilayer graphene. For magnetic fields $B>1$ T we observe the opening of a field induced gap at the charge neutrality point characterized by a diverging resistance. For higher fields the eight-fold degenerated lowest Landau level lifts completely. Both the sequence of this symmetry breaking and the strong transition of the gap-size point to a ferromagnetic nature of the insulating phase developing at the charge neutrality point.