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, G. Kotliar

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12 Scopus citations

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 (ω-1/5), 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.

Original languageEnglish (US)
Article number136406
JournalPhysical review letters
Volume124
Issue number13
DOIs
StatePublished - Apr 3 2020

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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