Emergent Chiral Metal near a Kondo Breakdown Quantum Phase Transition

Abstract

The destruction of the Kondo effect in a local-moment metal can lead to a topological non-Fermi-liquid phase, dubbed fractionalized Fermi liquid, with spinon-type excitations and an emergent gauge field. We demonstrate that, if the latter displays an internal $\pi$-flux structure, a chiral heavy-fermion metal emerges near the Kondo-breakdown transition. Utilizing a parton mean-field theory describing the transition between a conventional heavy Fermi liquid and a U(1) fractionalized Fermi liquid, we find a novel intermediate phase near the transition whose emergent flux pattern spontaneously breaks both translation and time-reversal symmetries. This phase is an orbital antiferromagnet, and we derive a Landau-type theory which shows that such a phase generically emerges from a $\pi$-flux spin liquid. We discuss the relevance to pertinent experiments.