Time-resolved collapse and revival of the Kondo state near a quantum phase transition

Abstract

One of the most successful paradigms of many-body physics is the concept of quasiparticles: excitations in strongly interacting matter behaving like weakly interacting particles in free space. Quasiparticles in metals are very robust objects. Yet, when a system's ground state undergoes a qualitative change at a quantum critical point (QCP), the quasiparticles may disintegrate and give way to an exotic quantum-fluid state of matter. The nature of this breakdown is intensely debated, because the emergent quantum fluid dominates the material properties up to high temperature and might even be related to the occurence of superconductivity in some compounds. Here we trace the dynamics of heavy-fermion quasiparticles in CeCu${}_{6-x}$Au${}_x$ and monitor their evolution towards the QCP in time-resolved experiments, supported by many-body calculations. A terahertz pulse disrupts the many-body heavy-fermion state. Under emission of a delayed, phase-coherent terahertz reflex the heavy-fermion state recovers, with a coherence time 100 times longer than typically associated with correlated metals. The quasiparticle weight collapses towards the QCP, yet its formation temperature remains constant -- phenomena believed to be mutually exclusive. Coexistence in the same experiment calls for revisions in our view on quantum criticality.

Published version, including data on CeCu6, CeCu5.9Au0.1, and CeCu5Au1 and extended Supplementary Information. 7 pages, 4 figures, Supplementary Information: 5 pages, 3 figures

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Cited by in corpus (14)

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• Ultrafast Laser Driven Many-Body Dynamics and Kondo Coherence Collapse
• Terahertz Conductivity of Heavy-fermion Systems from Time-resolved Spectroscopy
• Room Temperature Quantum Coherent Revival in an Ensemble of Artificial Atoms
• Transport Spectroscopy of the Field Induced Cascade of Lifshitz Transitions in YbRh2Si2
• Ultrafast Optical Control of Magnetic Order and Fermi Surface Topology at a Quantum Critical Point
• Phonons, Q-dependent Kondo spin fluctuations, and 4$\text{f}$/phonon resonance in YbAl${}_3$
• Magnetism trends in doped Ce-Cu intermetallics in the vicinity of quantum criticality: realistic Kondo lattice models based on dynamical mean-field theory
• Missing spectral weight in a heavy-fermion system far above Néel temperature
• Photo-induced nonlinear band shift and valence transition in SmS
• Kondo coherence versus superradiance in THz radiation-driven heavy-fermion systems