Probing Graphene on the Nanoscale: Rippling, Nanomembranes, and Confined states

Datum

07.06.2011

Zeit

16:40 - 18:10

Sprecher

Prof. Dr. Markus Morgenstern

Zugehörigkeit

II. Institute of Physics Band JARA - FIT , RWTH Aachen

Serie

TUD Physikalisches Kolloquium

Sprache

en

Hauptthema

Physik

Andere Themen

Physik

Host

Prof. Dr. Markus Morgenstern

Beschreibung

Spectroscopic measur ements are performed on graphene nanoislands, which exhibit confined states, mostly reproducible by tight - binding calculations. The islands are confined by zig - zag edges, which exhibit a peak at the Fermi level attributed to the predicted edge state. The s pin polarization of the latter is probed by spin - polarized scanning tunneling spectroscopy. Scanning tunneling microscopy and spectroscopy is applied to graphene at low temperature. It is shown that most graphene flakes on SiO2 exhibit an intrinsic rippling very similar to suspended flakes. This rippling is used to induce movements of the valleys by electrostatic forces of the tip. Thus, the valleys act as nanodrums consisting of only a few hundred atoms and imply ing extremely high resonance frequencies in the THz regime. The lateral compression induced by the lifting of valleys leads to a breaking of sublattice symmetry, presumably a buckled graphene phase with increased spin - orbit coupling.

Letztmalig verändert: 07.06.2011, 17:44:40