Abstract: Photoemission has developed into a powerful probe of condensed matter. Modern technical developments enable the study of not only the single-particle spectra but also the interaction with collective excitations. In this talk, we present an overview of the modern photoemission experiment with demonstrations of its application to the high-Tc superconductors.
The discovery of superconductivity in the cuprates resulted in a surge in research activity related to strongly correlated systems. Photoemission offers numerous insights into the doping-dependent phase diagrams of these complex materials, and we examine the properties as we move from the doped Mott insulating phase into the more metallic region. In particular, the latter region appears characterized by superconducting fluctuations suggestive of granular superconductivity.
The more recent discovery of high-Tc superconductivity in the iron-based systems, contrary to expectations, led to a resurgence of research activity in this area. We examine the application of photoemission to these multiband systems and contrast them with the cuprates. A more recent and powerful development in condensed matter physics has been the realization of the role of topology. In detailed studies of the iron-based superconductors, we examine systems where topology appears to interface with the world of high-Tc superconductivity. The presence of topological surface states allows us to study surface superconductivity at the solid-vacuum interface.
Bio: Peter Johnson, Head of the Electron Spectroscopy Group at Brookhaven National Laboratory, is an internationally recognized leader in photoelectron spectroscopy and its application to the study of electronic structure in condensed matter systems. His research has focused on low-dimensional systems including metallic surfaces, thin-film magnetism, and strongly correlated materials, particularly the high-temperature superconductors.