TY - JOUR
T1 - Global Phase Diagram of a Spin-Orbital Kondo Impurity Model and the Suppression of Fermi-Liquid Scale
AU - Wang, Y.
AU - Walter, E.
AU - Lee, S. S.B.
AU - Stadler, K. M.
AU - Von Delft, J.
AU - Weichselbaum, A.
AU - Kotliar, G.
N1 - Funding Information:
We thank H. Miao and R. Fernandes for helpful discussion. E. W., K. M. S., and J. vD. are supported by the Deutsche Forschungsgemeinschaft under Germany’s Excellence Strategy–EXC-2111-390814868, and S.-S. B. L. by Grant No. LE3883/2-1. A. W. was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-SC0012704. Y. W. and G. K. were supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences as a part of the Computational Materials Science Program through the Center for Computational Design of Functional Strongly Correlated Materials and Theoretical Spectroscopy.
Publisher Copyright:
© 2020 American Physical Society.
PY - 2020/4/3
Y1 - 2020/4/3
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85083755104&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85083755104&partnerID=8YFLogxK
U2 - 10.1103/PhysRevLett.124.136406
DO - 10.1103/PhysRevLett.124.136406
M3 - Article
C2 - 32302177
AN - SCOPUS:85083755104
SN - 0031-9007
VL - 124
JO - Physical Review Letters
JF - Physical Review Letters
IS - 13
M1 - 136406
ER -