Global Phase Diagram of a Spin-Orbital Kondo Impurity Model and the Suppression of Fermi-Liquid Scale

Y. Wang, E. Walter, S.-S. B. Lee, K. M. Stadler, J. von Delft, A. Weichselbaum, and G. Kotliar
Phys. Rev. Lett. 124, 136406 – Published 3 April 2020
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Abstract

Many correlated metallic materials are described by Landau Fermi-liquid theory at low energies, but for Hund metals the Fermi-liquid coherence scale TFL is found to be surprisingly small. In this Letter, we study the simplest impurity model relevant for Hund metals, the three-channel spin-orbital Kondo model, using the numerical renormalization group (NRG) method and compute its global phase diagram. In this framework, TFL becomes arbitrarily small close to two new quantum critical points that we identify by tuning the spin or spin-orbital Kondo couplings into the ferromagnetic regimes. We find quantum phase transitions to a singular Fermi-liquid or a novel non-Fermi-liquid phase. The new non-Fermi-liquid phase shows frustrated behavior involving alternating overscreenings in spin and orbital sectors, with universal power laws in the spin (ω1/5), orbital (ω1/5) and spin-orbital (ω1) dynamical susceptibilities. These power laws, and the NRG eigenlevel spectra, can be fully understood using conformal field theory arguments, which also clarify the nature of the non-Fermi-liquid phase.

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  • Received 4 November 2019
  • Accepted 28 February 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.136406

© 2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Y. Wang1, E. Walter2, S.-S. B. Lee2, K. M. Stadler2, J. von Delft2, A. Weichselbaum1,2, and G. Kotliar1,3

  • 1Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
  • 2Arnold Sommerfeld Center for Theoretical Physics, Center for NanoScience, and Munich Center for Quantum Science and Technology, Ludwig-Maximilians-Universität München, 80333 Munich, Germany
  • 3Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08856, USA

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Issue

Vol. 124, Iss. 13 — 3 April 2020

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