Professor Thorsten Hesjedal FInstP

Abstract:

We report on the functionality of our Thermoelectric Nanowire Characterization Platform (TNCP). As a proof of concept of our design, we present a set of experimental results obtained from the characterization of a single Bi2Te3 nanowire, allowing for the determination of the nanowire’s electrical conductivity and Seebeck coefficient.

Abstract:

After the discovery of Dirac fermions in graphene, it has become a natural question to ask whether it is possible to realize Dirac fermions in other two-dimensional (2D) materials as well. In this work, we report the discovery of multiple Dirac-like electronic bands in ultrathin Ge flms grown on Au(1 1 1) by angle-resolved photoelectron spectroscopy. By tuning the thickness of the flms, we are able to observe the evolution of their electronic structure when passing through the monolayer limit. Our discovery may signify the synthesis of germanene, a 2D honeycomb structure made of Ge, which is a promising platform for exploring exotic topological phenomena and enabling potential applications.

Abstract:

We present a structural and density functional theory study of FexCu1-xSe within the three-dimensional topological insulator Bi2Te3. The FexCu1-xSe inclusions are single-crystalline and epitaxially oriented with respect to the Bi2Te3 thin film. Aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy show an atomically-sharp FexCu1-xSe/Bi2Te3 interface. The FexCu1-xSe /Bi2Te3 interface is determined by Se-Te bonds and no misfit dislocations are observed, despite the different lattice symmetries and large lattice mismatch of ∼ 19%. First-principle calculations show that the large strain at the FexCu1-xSe /Bi2Te3 interface can be accommodated via van der Waals-like bonding between Se and Te atoms.