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.
@article{arxiv.1112.5368,
title = {Field induced quantum-Hall ferromagnetism in suspended bilayer graphene},
author = {H. J. van Elferen and A. Veligura and E. V. Kurganova and U. Zeitler and J. C. Maan and N. Tombros and I. J. Vera-Marun and B. J. van Wees},
journal= {arXiv preprint arXiv:1112.5368},
year = {2012}
}