Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 38: Theory of strongly correlated systems
MA 38.1: Topical Talk
Donnerstag, 15. März 2018, 09:30–10:00, H 0110
RKKY-induced Kondo breakdown near a magnetic quantum phase transiton — •Johann Kroha — Universität Bonn, Germany — CCM, Zhejiang University, Hangzhou, China
The fate of the fermionic quasiparticles near a magnetic quantum phase transition (QPT) in heavy-fermion (HF) compounds has been controversial for many years. It is generally believed that this Kondo destruction is driven by the critical fluctuations near the QPT. A novel renormalization group treatment of the quantum interference of Kondo and RKKY couplings shows, however, that the HF quasiparticles can be destroyed by the RKKY interaction even without critical fluctuations [1], with far reaching consequences for the QPT scenario: The lattice Kondo temperature, TK*(y), is suppressed in a universal way by the dimensionless RKKY coupling y, with a discontinuous breakdown at a critical value y=yc. This agrees quantitatively with STM spectroscopy on continuously tunable two-impurity Kondo systems [2]. We analyze in detail most recent time-resolved THz reflectometry experiments on the HF compound CeCu6−xAux across the QPT at x=0.1 [3]. The theoretical as well as the experimental findings point to a new quantum critical scenario, realized in CeCu6−xAux, where the HF quasiparticles disintegrate in that their spectral weight vanishes continuously, but TK*(y) remains finite. This is consistent with ω/T scaling as an indicator for critical Kondo destruction.
[1] A. Nejati, K. Ballmann, J. Kroha, PRL 118, 117204 (2017)
[2] J. Bork, Y.-H. Zhang, L. Diekhöhner et al., Nature Phys. 7, 901 (2011)
[3] Ch. Wetli, J. Kroha, K. Kliemt et al., arXiv:1703.04443