Understanding the behavior of electrons in matter: from topology to correlation
Abstract: The assumption that electrons in a metal behave like free electrons in a vacuum might seem absurd, but it holds surprisingly well for various materials. The electronic properties of some very common materials can be explained by just assuming the electrons do not interact with each other, which has laid the basis for much of the single-electron theory that is currently used. The past half-century has however yielded more and more examples of systems exhibiting physics governed by the interactions between electrons, challenging our understanding based on the single-electron perspective. While the properties of such materials are sometimes described as ‘exotic’, they represent a new and exciting area in solid-state physics, as they often originate from new electronic phases.
In order to investigate such unconventional materials and assay claims based on novel theories attempting to describe the underlying physics, increasingly complex experiments are performed. In this context, two cases will be discussed, deviating from the conventional single-electron picture in different extremes. In one extreme, electrons are protected from all forms of interaction by emergent topology in graphene, while the other extreme shows emergent behavior due to strong interactions between the electrons in heavily doped graphene. The contrast between these wildly different physics in the same material is symbolic of the field of condensed matter physics and hopefully inspires more experiments to be performed, to contribute to our understanding of these interesting and beautiful physics.
Bio: Niels obtained his PhD from Eindhoven University of Technology where he studied topology and non-Fermi liquid physics in two-dimensional materials using scanning tunneling spectroscopy. He subsequently worked on developing a new approach to time-of-flight electron energy loss spectroscopy as well as the construction a low-temperature UHV length-extension resonator-based hybrid AFM/STM with Prof. Jom Luiten and Kees Flipse at Eindhoven University of Technology. He has recently joined UIUC to study the collective interactions between electrons in high-temperature superconductors and other strongly correlated electron systems
About the QSQM: The EFRC-QSQM center aims to develop and apply nontrivial quantum sensing to measure and correlate local and nonlocal quantum observables in exotic superconductors, topological crystalline insulators, and strange metals. The center is led by the University of Illinois at Urbana-Champaign in partnership with the University of Illinois at Chicago and the SLAC National Accelerator Laboratory.
