Interfacing 3D topological insulator BSTS. Nick de Jong's paper is now out in PRB on the electronic structure of interfaces between the bulk insulating 3D topological insulator BSTS and a commonly used contact metal (Ag), a magnetic metal (Fe) and a superconductor (Nb) metal on the bulk TI BSTS.
Nick found that for all coverages at room temperature and <0.2 ML coverages at 40K that all three metals shift the chemical potential up, increasing the binding energy of the Dirac point. For deposition and measurement at low T, after the initial increase in Dirac point binding energy (upward shift of chemical potential, donor behaviour of the metal overlayer), the behaviour reverses and the chemical potential them moves downward, reducing the Dirac point energy (acceptor behaviour of the metals). For silver this switch goes together with formation of substitutional defects (AgTe,Se), but for the less mobile Fe and Nb it is linked to clustering of the adatoms on the surface.
Pick up the paper in the publications section of the webpage, or click here.
The experiments were carried at the 1^2 end-station at BESSY-II/HZB in Berlin.
This research is part of the FOM/NWO-N Programme 134 'Topological Insulators', which combines the forces of groups from Leiden, Delft, Amsterdam & Twente, and is led by the Mark Golden in Amsterdam.