Synchrotron-radiation studies of topological insulators

Topological insulators (TIs) are a recently discovered class of quantum materials that are currently attracting considerable attention. The most interesting aspect of the TIs is, in fact, not that they are bulk insulators but that their surfaces support localized metallic states with some special properties, among others a characteristic spin texture. Most importantly, the existence of these metallic states is not a a surface property; it is required by the topology of the bulk band structure. This Chapter gives an accessible introduction into the physics and band structure of TI materials and into the study of TIs with synchrotron radiation-based techniques, in particular angle-resolved photoemission spectroscopy (ARPES).