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arXiv · 2004.07719

Terahertz Conductivity of Heavy-fermion Systems from Time-resolved Spectroscopy

Chia-Jung Yang·Shovon Pal·Farzaneh Zamani·Kristin Kliemt·Cornelius Krellner·Oliver Stockert·Hilbert v. Löhneysen·Johann Kroha·Manfred Fiebig
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Abstract

The Drude model describes the free-electron conduction in simple metals, governed by the freedom that the mobile electrons have within the material. In strongly correlated systems, however, a significant deviation of the optical conductivity from the simple metallic Drude behavior is observed. Here, we investigate the optical conductivity of the heavy-fermion system CeCu$_{\mathrm{6-x}}$Au$_{\mathrm{x}}$, using time-resolved, phase-sensitive terahertz spectroscopy. Terahertz electric field creates two types of excitations in heavy-fermion materials: First, the intraband excitations that leave the heavy quasiparticles intact. Second, the resonant interband transitions between the heavy and light parts of the hybridized conduction band that break the Kondo singlet. We find that the Kondo-singlet breaking interband transitions do not create a Drude peak, while the Kondo-retaining intraband excitations yield the expected Drude response; thus, making it possible to separate these two fundamentally different correlated contributions to the optical conductivity.

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Chia-Jung Yang, Shovon Pal, Farzaneh Zamani, Kristin Kliemt, Cornelius Krellner, Oliver Stockert, Hilbert v. Löhneysen, Johann Kroha, Manfred Fiebig. 2020-04-16. Terahertz Conductivity of Heavy-fermion Systems from Time-resolved Spectroscopy. https://doi.org/10.1103/physrevresearch.2.033296

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