SU(4) symmetry breaking revealed by magneto-optical spectroscopy in epitaxial graphene

Liang Tan (1) , Milan Orlita (2) , Marek Potemski (2) , James Palmer (3) , Claire Berger (4, 3) , Walter A. de Heer (3) , Steven G Louie (1) , Gérard Martinez (2)

1 LBNL - Lawrence Berkeley National Laboratory [Berkeley]
2 LNCMI-G - Laboratoire national des champs magnétiques intenses - Grenoble
3 Georgia Institute of Technology [Atlanta]
4 NEEL - QuantECA - Circuits électroniques quantiques Alpes

Refined infra-red magneto-transmission experiments have been performed in magnetic fields B up to 35 T on a series of multi-layer epitaxial graphene samples. Following the main optical transition involving the n = 0 Landau level, we observe a new absorption transition increasing in intensity with magnetic fields B ≥ 26T. Our analysis shows that this is a signature of the breaking of the SU(4) symmetry of the n = 0 LL. Using a quantitative model, we show that the only symmetry breaking scheme consistent with our experiments is a charge density wave (CDW).

Domaines: Matière Condensée [cond-mat]

Liang Tan, Milan Orlita, Marek Potemski, James Palmer, Claire Berger, et al.. SU(4) symmetry breaking revealed by magneto-optical spectroscopy in epitaxial graphene. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2015, 91 (23), pp.235122. ⟨10.1103/PhysRevB.91.235122⟩. ⟨hal-01859511⟩