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TT: Fachverband Tiefe Temperaturen
TT 11: Heavy Fermions
TT 11.9: Vortrag
Montag, 18. März 2024, 17:15–17:30, H 3005
Kondo physics and magnetism with high-order Van Hove singularities — •Krzysztof P. Wójcik1, Johann Kroha2,3, and Peter Wahl3,2 — 1Institute of Molecular Physics, Polish Academy of Sciences, Poznań, Poland — 2Physikalisches Institut, Universität Bonn, Germany — 3SUPA, School of Physics and Astronomy, University of St Andrews, United Kingdom
Despite vast experimental progress in strongly-correlated electron research over last decades, a number of major puzzles remain unsolved. In particular, in some materials (e.g. strontium ruthenates) the nature of magnetic-field-driven quantum criticality has not been determined. It may be caused mainly by quantum fluctuations, or rather a second-order Van Hove singularity present near the Fermi level may play the major role [1]. To better understand the tension between these two mechanisms, an analysis of a simple impurity model is proposed, which can clarify the fate of the Kondo effect in the host exhibiting a spin-split Van Hove singularity.
The model is solved with numerical renormalization group. It is shown that the spin-splitting of the band stabilizes a novel strong-coupling partially polarized fixed point. Such splitting is seen experimentally in surface spectroscopy of Sr3Ru2O7, even in the absence of external magnetic field [1]. The results concerning spin susceptibility and entropy will be presented, followed by the predictions of spectral properties and discussion of their significance for the correlated lattices.
[1] C. A. Marques et al., Sci. Adv. 8 (2022) eabo7757.
Keywords: Kondo effect; Van Hove singularity; magnetism; Heavy Fermions; numerical renormalization group