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TT: Fachverband Tiefe Temperaturen
TT 47: Quantum-Critical Phenomena
TT 47.1: Talk
Thursday, March 30, 2023, 09:30–09:45, HSZ 204
The mystery of the missing heavy-fermion weight — •Chia-Jung Yang1, Oliver Stockert2, Hilbert v. Löhneysen3, Shovon Pal1,4, Johann Kroha5, and Manfred Fiebig1 — 1Department of Materials, ETH Zurich, Switzerland — 2MPI for Chemical Physics of Solids, Dresden, Germany — 3KIT Karlsruhe, Germany — 4School of Physical Science, NISER Bhubaneshwar, India — 5University of Bonn, Germany
The fermionic quasiparticle weight is one of the keys to understanding the quantum critical scenarios across a quantum phase transition (QPT). In heavy-fermion compounds, CeCu6−xAux (CCA), Cu substitution by Au expands the lattice, thereby inducing a QPT at x = 0.1 from a paramagnetic Fermi-liquid state to an antiferromagnetically-ordered ground state. Recently, the evolution of spectral weight has been revealed in CCA at x = 0, 0.1, and 1.0 via terahertz (THz) time-domain spectroscopy [1,2]. Here, we further investigate the spectral weight within the RKKY-dominated region where x = 0.2 and 0.3. In both samples, we find that the spectral weight increases slightly with decreasing temperature (T), but settles at a strongly suppressed, T-independent value already at and below 100 K, about two orders of magnitude above the Néel temperature [3]. This indicates that across QPT in CCA, the Kondo singlet formation is suppressed by the T-independent RKKY interaction, not by the critical magnetic fluctuations, in agreement with theoretical predictions [4].
[1] Nat. Phys. 14, 1103 (2018)
[2] PRR 2, 033296 (2020)
[3] Eur. Phys. J. B 5, 447 (1998)
[4] PRL 118, 117204 (2017)