Tunneling Magneto-Conductance Oscillations in Epitaxial Graphene

Scanning tunneling microscopy (STM) and spectroscopy (STS) at a temperature of 4 K are used to study the electronic properties of epitaxial graphene on SiC in a magnetic field applied perpendicular to the graphene plane. While changing the magnetic field we observe oscillations in the tunneling conductance, dI/dV (tunneling magneto-conductance oscillations, or TMCO). These are similar to Shubnikov-de Haas oscillations of magnetoresistance, but differ in important aspects. Magnetic field scans acquired at multiple tunneling injection energies allow us to create a density-of-states contour map as a function of both in energy and magnetic field. The data are well-described by the monolayer-graphene density of states, with small additional features that may indicate coherent effects. This work was supported in part by NSF, NRI-INDEX, and the W. M. Keck Foundation.