Journal: Physical Review Letters

Abstract: Many correlated metallic materials are described by Landau Fermi-liquid theory at low energies, but for Hund metals the Fermi-liquid coherence scale T_FL 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, T_FL 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 (ω^+1/5) and spin-orbital (ω^+1) 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.

First Author: Y. Wang

Co-author: E. Walter,S.-S. B. Lee,K. M. Stadler,J. von Delft,A. Weichselbaum

Indexed by: Journal paper

Correspondence Author: G. Kotliar

Discipline: Natural Science

Volume: 124

Issue: 13

Page Number: 136406-136413

Translation or Not: no

Date of Publication: 2020-04-03

Included Journals: SCI、SSCI

Links to published journals: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.136406