Philip Hofmann IFA Basic electronic properties of graphene and topological insulators Time: Tuesday, October 6, 15.15 to 16.00 Place: Fysisk Auditorium Both graphene and the so-called topological insulators are thought to have great potential as materials for electronics and spintronics, respectively. In this talk, I will report very recent results from both systems, obtained with synchrotron radiation-based angle- and spin-resolved spectroscopy. I will also use the opportunity to outline future perspectives for similar techniques on ASTRID2. In graphene, the electronic structure near the Fermi energy is analogous to that of massless Dirac Fermions and many of graphene's promising properties are derived from this. One essential drawback for graphene-based electronic elements, however, is the lack of a band-gap around the Fermi level, the very feature which enables us to control the carrier density in a semiconductor. In the first part of the talk, I will show how a large band gap can be induced in a graphene layer which is adsorbed on an Ir(111) surface, by the controlled and patterned adsorption of atomic hydrogen. Topological insulators are a recently discovered and conceptually new class of materials. On the face of it, they are well-known, off-the-shelf compounds, but they have a previously overlooked and profound property which forces their surfaces and edges to be metallic, in contrast to the insulating inner material. These metallic surfaces have therefore been called "topological metals". An important example of such a topological metal appears in the quantum spin Hall effect, which was discovered in 2007. In the second part of the talk, I will discuss the possibility of using a vicinal surface of the semimetal bismuth as a model system for a one-dimensional topological metal which would act as a perfect quantum-conducting spin-filter and which strongly resembles one single edge of the spin quantum Hall effect. Peter Staanum and Nicolai Nygaard Coffee, tea and fruit will be served at 15.05 ---------------------------------- Peter Frøhlich Staanum Department of Physics and Astronomy University of Aarhus Ny Munkegade 120 8000 Aarhus C Denmark Phone: (+45) 8942 3602 Fax: (+45) 8612 0740 VAT Nr.: DK16562777 EAN Nr.: 5798000419872 ----------------------------------