期刊
PHYSICAL REVIEW X
卷 10, 期 3, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevX.10.031052
关键词
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资金
- Deutsche Forschungsgemeinschaft under Germany's Excellence Strategy [EXC-2111-390814868, LE3883/2-1]
- U.S. Department of Energy, Office of Basic Energy Sciences [DE-SC0012704]
- National Science Foundation [DMR-1733071]
- U.S. Department of Energy, Office of Science, Basic Energy Sciences, Computational Materials Science Program through the Center for Computational Design of Functional Strongly Correlated Materials and Theoretical Spectroscopy
Hund metals have attracted attention in recent years due to their unconventional superconductivity, which supposedly originates from non-Fermi-liquid (NFL) properties of the normal state. When studying Hund metals using dynamical mean-field theory, one arrives at a self-consistent Hund impurity problem involving a multiorbital quantum impurity with nonzero Hund coupling interacting with a metallic bath. If its spin and orbital degrees of freedom are screened at different energy scales, T-sp < T-orb, the intermediate energy window is governed by a novel NFL fixed point, whose nature had not yet been clarified. We resolve this problem by providing an analytical solution of a paradigmatic example of a Hund impurity problem, involving two spin and three orbital degrees of freedom. To this end, we combine a state-ofthe-art implementation of the numerical renormalization group, capable of exploiting non-Abelian symmetries, with a generalization of Affleck and Ludwig's conformal field theory (CFT) approach for multichannel Kondo models. We characterize the NFL fixed point of Hund metals in detail for a Kondo model with an impurity forming an SU(2) x SU(3) spin-orbital multiplet, tuned such that the NFL energy window is very wide. The impurity's spin and orbital susceptibilities then exhibit striking power-law behavior, which we explain using CFT arguments. We find excellent agreement between CFT predictions and numerical renormalization group results. Our main physical conclusion is that the regime of spin-orbital separation, where orbital degrees of freedom have been screened but spin degrees of freedom have not, features anomalously strong local spin fluctuations: the impurity susceptibility increases as chi(imp)(sp) similar to omega(-gamma), with gamma > 1.
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