Are strange metals hydrodynamic or quantum critical?

• Applicant: Professor Dr. Jörg Schmalian
• Subject Area: Theoretical Condensed Matter Physics ; Experimental Condensed Matter Physics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 568833081

Understanding scenarios in which strong interactions between itinerant electrons and collective quantum fluctuations invalidate the conventional Landau Fermi-liquid paradigm is a central problem in the field of correlated metals The objective of this joint initiative is to experimentally and theoretically investigate and elucidate strange metal (SM) behavior in Non-Fermi liquid quantum materials with a specific focus on: i) identifying distinct fingerprints of thermoelectric and magnetic field-driven SM transport; ii) elucidating the role of disorder in the emergence of a SM; and iii) determining the placement of SM behaviour within the continuum of hydrodynamic and quantum critical transport. To this end, we will conduct transport experiments to measure resistivity, thermoelectric power, and magneto-transport in candidate materials for strange metal physics and systematically tune the disorder concentration via irradiation. In parallel, we will advance the theory of magneto- and thermoelectric transport in strange metals, jointly refining the quantum Boltzmann formalism and non-quasiparticle transport as derived from the solution of generalised Yukawa-Sachdev-Ye-Kitaev (YSYK) models. These investigations will fill gaps in both the experimental and theoretical state of the art. Their synthesis shall elucidate the underlying mechanism of the strange metal state.

• DFG Programme: Research Grants
• International Connection: France
• Cooperation Partners: Professor Blaise Goutereaux, Ph.D.; Professor Gaël Grissonnanche, Ph.D.