SKM 2023 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 47: Quantum-Critical Phenomena

TT 47.1: Vortrag

Donnerstag, 30. März 2023, 09:30–09:45, HSZ 204

The mystery of the missing heavy-fermion weight — •Chia-Jung Yang¹, Oliver Stockert², Hilbert v. Löhneysen³, Shovon Pal^1,4, 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, CeCu_6−xAu_x (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)