Dresden 2026 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 14: Superconductivity: Properties and Electronic Structure

TT 14.3: Vortrag

Montag, 9. März 2026, 15:30–15:45, HSZ/0103

Strange metals studied by EELS and RIXS — •Jörg Fink — IFW-Dresden, Dresden, Germany

Strange metal behavior, which occurs above the dome of unconventional superconductivity is characterized by a linear temperature dependence of the resistivity. This signals a breakdown of the quasiparticle concept used in normal Fermi liquids. In the phenomenological marginal Fermi liquid (MFL) theory the behavior is related to a continuum of low-energy electronic excitations. Holographic theories have predicted that this continuum causes an overdamping of plasmon excitations. On the other hand, our EELS and RIXS experiments reveal well pronounced optical and acoustic plasmons in cuprates and ruthenates. The contradiction can be explained by an energy-dependent effective mass related to a strong coupling of the charge carriers to an oscillator at about 0.4 eV also detected in ARPES experiments. Moreover, this energy is used as a cutoff energy in the MFL theory. The oscillator energy is well below the plasmon energies which leads to resilient quasiparticles at high energy. Possibly, the oscillator is related to a coupling of the charge carriers to spin fluctuations.

Keywords: Strange metals; Self-energies; Plasmons; Holographic theories; Electron Energy-Loss Spectroscopy