TY - JOUR
T1 - Missing spectral weight in a heavy-fermion system far above Néel temperature
AU - Li, Jingwen
AU - Priyadarshi, Debankit
AU - Yang, Chia-Jung
AU - Pohl, Ulli
AU - Stockert, Oliver
AU - von Löhneysen, Hilbert
AU - Pal, Shovon
AU - Fiebig, Manfred
AU - Kroha, Johann
N1 - Funding: J.L., D.P., C.-J.Y., and M.F. acknowledge the financial support from the Swiss National Science Foundation through Projects No. 200021_178825 and No. 200021_219807. S.P. acknowledges the support from the Department of Atomic Energy (DAE) through the project Basic Research in Physical and Multidisciplinary Sciences via No. RIN4001. S.P. also acknowledges the startup support from DAE through the National Institute of Science Education and Research and the Science and Engineering Research Board (SERB) through a SERB Start-up Research Grant (SRG) via Project No. SRG/2022/000290. U.P. and J.K. acknowledge the support of the Deutsche Forschungsgemeinschaft via TRR 185 (No. 277625399) OSCAR, project C4, and the Cluster of Excellence ML4Q (No. 90534769).
PY - 2025/1/15
Y1 - 2025/1/15
N2 - The competition between the Kondo spin-screening effect and the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in heavy-fermion systems drives the quantum phase transition (QPT) between the magnetically ordered and the heavy-Fermi-liquid ground states. Despite intensive investigations of heavy quasiparticles on the Kondo-screened side of the QPT and of their breakdown at the quantum critical point, the magnetically ordering side has not systematically been studied. Using terahertz time-domain spectroscopy, we report a suppression of the Kondo quasiparticle weight in CeCu6−𝑥Au𝑥 samples on the antiferromagnetic (AFM) side of the QPT at temperatures as much as two orders of magnitude above the Néel temperature 𝑇N. With our systematic investigations into the high-temperature, paramagnetic region on the AFM side of the phase diagram of CeCu6−𝑥Au𝑥, i.e., with 𝑥 = 0.2, 0.3, and 0.5, we show that the suppression results from a quantum frustration effect induced by the temperature-independent RKKY interaction. Hence, our results emphasize that, in addition to critical fluctuations, the RKKY interaction may play an important role in the quantum-critical scenario.
AB - The competition between the Kondo spin-screening effect and the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in heavy-fermion systems drives the quantum phase transition (QPT) between the magnetically ordered and the heavy-Fermi-liquid ground states. Despite intensive investigations of heavy quasiparticles on the Kondo-screened side of the QPT and of their breakdown at the quantum critical point, the magnetically ordering side has not systematically been studied. Using terahertz time-domain spectroscopy, we report a suppression of the Kondo quasiparticle weight in CeCu6−𝑥Au𝑥 samples on the antiferromagnetic (AFM) side of the QPT at temperatures as much as two orders of magnitude above the Néel temperature 𝑇N. With our systematic investigations into the high-temperature, paramagnetic region on the AFM side of the phase diagram of CeCu6−𝑥Au𝑥, i.e., with 𝑥 = 0.2, 0.3, and 0.5, we show that the suppression results from a quantum frustration effect induced by the temperature-independent RKKY interaction. Hence, our results emphasize that, in addition to critical fluctuations, the RKKY interaction may play an important role in the quantum-critical scenario.
UR - https://www.scopus.com/pages/publications/85217757560
U2 - 10.1103/PhysRevB.111.035117
DO - 10.1103/PhysRevB.111.035117
M3 - Article
SN - 2469-9950
VL - 111
JO - Physical Review B
JF - Physical Review B
IS - 3
M1 - 035117
ER -