Dresden 2020 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 42: Correlated Electrons: f-Electron Systems and Heavy Fermions 2
TT 42.9: Talk
Wednesday, March 18, 2020, 17:15–17:30, HSZ 204
Terahertz conductivity of heavy-fermion systems from time-resolved spectroscopy — •C.-J. Yang1, S. Pal1, F. Zamani2, K. Kliemt3, C. Krellner3, O. Stockert4, H. v. Löehneysen5, J. Kroha2, and M. Fiebig1 — 1ETH Zürich, Switzerland — 2University of Bonn, Germany — 3Goethe-University Frankfurt, Germany — 4MPI CPfS Dresden, Germany — 5KIT Karlsruhe, Germany
Ultrafast, phase-sensitive terahertz (THz) spectroscopy has recently been introduced as a novel tool to investigate the quasiparticle (QP) dynamics across the quantum phase transition in heavy-fermion compounds [1,2]. The incident THz pulse with a spectral range of 0–3 THz creates collective intraband excitations within the heavy band as well as resonant interband transitions between the hybridizing heavy and light parts of the conduction band. The latter break the Kondo singlet and thus lead to a time-delayed echo-like response [1,2]. By contrast, the intraband excitations leave the heavy quasiparticles intact and are expected to be Fermi-liquid Drude response. Our time-resolved phase-sensitive measurements of the electric field response enables us to separate both types of excitations by their delay time and to derive their individual contributions to the THz optical conductivity. While the Kondo-breaking interband transitions create no Drude peak, the intraband excitations recover the Drude response as expected. It is thus possible to separate strongly and weakly correlated electronic contributions to the optical conductivity.
[1] C. Wetli et al., Nat. Phys. 14, 1103 (2018)
[2] S. Pal et al., PRL 122, 096401 (2019)
[3] C.-J. Yang et al., under prep. (2019)