Exploring the electronic properties of novel spintronic materials by photoelectron spectroscopy

The presented thesis deals with the electronic and structural surface properties of two important material classes: Topological insulators and half-metallic Heusler alloys. In the ideal case these are predicted to show a full spin polarization at the Fermi energy and therefore are potential candidates for future spintronic applications. In the case of the topological insulators, the electronic band structure of thin Bi2Te3 and Sb2Te3 films was extensively studied by means of spin- and angle-resolved photoemission spectroscopy. The experimental determination of topologically protected robust and spin-polarized surface states was of particular interest. A detailed analysis of the observed results was performed within the density functional theory employing the local-density approximation. In this work, also the influence of various in situ cleaning procedures for obtaining atomically clean and well-ordered topological insulator surfaces was investigated. The Bi2Te3 and Sb2Te3 thin film surfaces studied were successfully cleaned and subsequently characterized by photomission spectroscopy.