Strange Metals in Quantum Materials and Quantum Emulators

Strange metals are one of the most prominent frontiers of condensed matter physics. While conventional metals are well described by Landau’s Fermi liquid theory – i.e. a quantum liquid of long-lived, local, electron-like quasiparticles – strange metals defy this paradigm. Here, the local low-energy excitations are extremely short lived and the adiabatic connection to free electrons breaks down. As a consequence, strange metals display a multitude of unusual experimental phenomena, including anomalous charge transport (for example linear in temperature and magnetic field scaling of resistance), singular thermodynamics, and characteristic dynamical scaling. Experimentally, strange metallic behavior has been reported in a variety of experimental systems including high-temperature superconductors and heavy fermion materials. Recent progress in experimental control and device fabrication not only allowed for much more accurate studies of these classic materials, but, in the process, also revealed strikingly new properties such as the unexpectedly simple and yet puzzle scaling of the magnetoresistance. Present-day technology adds novel quantum emulators such as twisted van-der-Waals heterostructures and cold atomic gases to the list of experimental systems displaying strange metallic behavior. At the same time, most recent theories explaining strange metallic behavior resort – from a healthy variation of perspectives – to such diverse concepts as exotic (beyond-Landau) critical quantum fluctuations, effective dual gravity models, and quantum hydrodynamics. As such, this WE-Heraeus Seminar aims at bringing together key figures in the research on strange metals. A particularly important mission is the fruitful cross-talks between experimentalists working on a variety of platforms, as well as theorists with different perspectives of the problem.