Sequential Localization and Strange-metal Behavior in a Multipolar Kondo System*

Quantum criticality and beyond-Landau physics of Kondo destruction [1,2] in heavy fermion systems with multipolar degrees of freedom is attracting considerable interest. Recent experiments on the heavy fermion compound Ce₃Pd₂₀Si₆ show evidence of two consecutive Fermi surface collapsing quantum critical points (QCP) as it is tuned from a paramagnetic to an antiferroquadrupolar (AFQ) and then to an antiferromagnetic (AFM) state [3]. We are able to understand this behavior by advancing a theory of sequential destruction of an SU(4) spin-orbital-coupled Kondo entanglement in an SU(4) Bose-Fermi Kondo model, which represents an effective model for a multipolar Kondo lattice system with Kugel–Khomskii interaction. As a function of coupling strength to the bosonic bath, we find that a generic trajectory in the parameter space contains two QCPs associated with the Kondo destruction of the orbital and spin degrees of freedom, respectively. For a Kondo lattice, this corresponds to two stages of Fermi surface jump, thus providing a natural understanding of the experimental findings.
[1] Q. Si et al., Nature 413, 804 (2001).
[2] S. Paschen et al., Nature 432, 881 (2004).
[3] V. Martelli, A. Cai, et al., arXiv:1709.09376.