------------------------------------------------------------------------------------------------------
Date: Monday November 29, 2010
Time: 11:00
Place: HPF G 6
Host: Atac Imamoglu
Probing spins and ripples in graphene with an in-plane magnetic field
Mark Lundeberg
University of British Columbia, Vancouver, Canada
Since the early days of the graphene boom, perpendicular magnetic fields have been used to to reveal graphene's unusual properties through the quantum Hall effect. This effect occurs due to the strong coupling of magnetic fields to the electrons charge, which easily overwhelms the coupling to their spins. The charge coupling can be turned off, however, by rotating the magnetic field to be parallel to the two-dimensional graphene sheet. By applying such in-plane magnetic fields, we were able to directly observe spin splitting of the electron sea in graphene. In practice, a small amount of charge coupling does remain since graphene devices have a naturally rippled topography when placed on a rough substrate. This results in experimentally observable random magnetic field effects when a uniform in-plane field is applied, allowing the ripple size to be estimated.