Quantum Criticality Enabled by Intertwined Degrees of Freedom

TL;DR

This paper investigates quantum criticality in systems with intertwined degrees of freedom, revealing two distinct quantum critical points related to Kondo entanglement destruction, and offers insights into strange metals and heavy fermion behaviors.

Contribution

It introduces a renormalization-group analysis of a multipolar Kondo model, uncovering dual quantum critical points and expanding understanding of quantum criticality in complex correlated systems.

Findings

Identification of two quantum critical points in the model

Theoretical explanation for experimental observations in multipolar heavy fermion metals

Proposal of new avenues for designing quantum critical systems

Abstract

Strange metals appear in a wide range of correlated materials. Electronic localization-delocalization and the expected loss of quasiparticles characterize beyond-Landau metallic quantum critical points and the associated strange metals. Typical settings involve local spins. Systems that contain entwined degrees of freedom offer new platforms to realize novel forms of quantum criticality. Here, we study the fate of an SU(4) spin-orbital Kondo state in a multipolar Bose-Fermi Kondo model, which provides an effective description of a multipolar Kondo lattice, using a renormalization-group method. We show that at zero temperature a generic trajectory in the model's parameter space contains two quantum critical points, which are associated with the destruction of Kondo entanglement in the orbital and spin channels respectively. Our asymptotically exact results reveal an overall phase diagram, provide the theoretical basis to understand puzzling recent experiments of a multipolar heavy fermion metal, and point to a means of designing new forms of quantum criticality and strange metallicity in a variety of strongly correlated systems.