We present energy-momentum mapping of the photocurrent in the Dirac cone of the topological insulator Sb$_2$Te$_3$ by means of time and angle-resolved two-photon photoemission (2PPE) after optical excitation with ultrashort linear and circular polarized mid-infrared laser pulses. Recently, we have demonstrated that linear polarized mid-infrared pulses permit the generation of photocurrents...
The transition metal dichalcogenide IrTe$_2$ undergoes two first-order structural and charge-ordered phase transitions on cooling below 270 K and below 180 K. It has been put forward that a Mott phase involving spin-orbit-coupled states [1] may be at the origin of the phase transitions in IrTe$_2$.
Here we present a time-resolved angle-resolved photoelectron spectroscopy study of IrTe$_2$ [2]....
Topological insulators (TIs) host metallic topological surface states with helical spin structure. This makes them promising materials for the generation of spin-polarized currents. The TI Bi$_2$Se$_3$ is intrinsically n-doped and thus the topological surface states at the Γ point with a Dirac cone (DC) dispersion is occupied. Two-photon photoemission experiments have shown that Bi$_2$Se$_3$...
Ab-initio electronic structure calculations have become increasingly reliable and successful in describing relatively complex surfaces or interfaces consisting of hundreds of atoms. However, it is often difficult to extract general trends or to obtain a more global picture. In this talk, I will first present an ab-initio-based model potential which is able to predict the energy position and...