| AVS 57th International Symposium & Exhibition | |
| Graphene Focus Topic | Monday Sessions |
| Session GR+SS+TF+EM-MoM |
| Session: | Epitaxial Graphene on SiC |
| Presenter: | Y.J. Song, CNST/NIST; Maryland NanoCenter UMD |
| Authors: | Y.J. Song, CNST/NIST; Maryland NanoCenter UMD A.F. Otte, CNST/NIST; Maryland NanoCenter UMD D.B. Torrance, Georgia Institute of Technology Y. Hu, Georgia Institute of Technology P.N. First, Georgia Institute of Technology W.A. de Heer, Georgia Institute of Technology J.A. Stroscio, CNST/NIST |
| Correspondent: | Click to Email |
Landau levels on epitaxially grown graphene were recently mapped both spatially and energetically using scanning tunneling spectroscopy in magnetic fields at 4 K [1]. In this talk we present new measurements, made at ≈10 mK, of all four electron states resulting from the lifting of the fourfold spin- and valley-degeneracy of the N = 1 Landau level in applied magnetic fields. We show that the energy splitting from the broken valley degeneracy is ten times larger than electron spin splitting in our samples. When the Fermi level lies inside the four-fold Landau manifold, significant electron correlation effects result in an enhanced valley splitting at even filling factors, and an enhanced electron spin splitting at odd filling factors. Most surprisingly, we observe new many body states with top-layer Landau level filling factors 7/2, 9/2, and 11/2.
[1] David L. Miller, Kevin D. Kubista, Gregory M. Rutter, Ming Ruan, Walt A. de Heer, Phillip N. First, and Joseph A. Stroscio, Science 324, 924-927 (2009).