The Impact Of Spin-Orbit Interaction On The Image States Of High-Z Materials

Due to many important technical developments over the past two decades angle-resolved (inverse) photoemission has become the method of choice to study experimentally the bulk and surface-related electronic states of solids in the most detailed way. Due to new powerful photon sources as well as efficient analyzers and detectors extremely high energy and angle resolution are achieved nowadays for spin-integrated and also for spin-resolved measurements. These developments allow in particular to explore the influence of spin-orbit coupling on image potential states of simple metals like Ir, Pt, or Au with a high atomic number as well as new types of materials as for example topological insulators. Herein, fully relativistic angle- and spin-resolved inverse photoemission calculations are presented that make use of the spin-density matrix formulation of the one-step model. This way a quantitative analysis of all occupied and unoccupied electronic features in the vicinity of the Fermi level is achieved for a wide range of excitation energies. Using this approach, in addition, it is possible to deal with arbitrarily ordered but also disordered systems. Because of these features, the one-step or spectral function approach to photoemission permits detailed theoretical studies on a large variety of interesting solid-state systems.yy