Quantum Criticality and Sequential Destruction of Spin-Orbital-coupled Kondo Effect**

Quantum critical points (QCPs) and the beyond-Landau physics of Kondo destruction [1,2] are being studied in systems with multipolar degrees of freedom. The compound Ce₃Pd₂₀Si₆ shows evidence for two consecutive Fermi surface collapsing QCPs as it is tuned from a paramagnetic to an antiferroquadrupolar and then to an antiferromagnetic state [3]. A theory was advanced [3] for a sequential destruction of spin-orbital-coupled Kondo effect in an SU(4) Bose-Fermi Kondo model, an effective model for a multipolar Kondo lattice. Here we report an analytical renormalization group calculation of the model with Ising anisotropy. We show that a generic trajectory in the parameter space contains two QCPs associated with the destruction of the orbital and spin Kondo effects, respectively. Our work establishes a firm theoretical ground for the notion of sequential Kondo destruction. Implications for metallic quantum criticality in general are discussed.

[1] Q. Si et al, Nature 413, 804 (2001)
[2] S. Paschen et al, Nature 432, 881 (2004)
[3] V. Martelli, A. Cai, E. Nica, M. Taupin, A. Prokofiev, C.-C. Liu, H. Lai, R. Yu, K. Ingersent, R. Küchler, A. M. Strydom, D. Geiger, J. Haenel, J. Larrea, Q. Si, S. Paschen, PNAS 116, 17701 (2019)