Bose Fermi Kondo model from a large S expansion -- quantum criticality and non-Fermi liquid behavio

The quantum critical phenomena associated with the destruction of the Kondo effect in heavy fermion systems lie beyond the Ginzburg-Landau framework [1,2]. The Bose-Fermi Kondo model provides an effective model to describe the Kondo destruction quantum criticality, displaying such unconventional physics as the Planckian dynamical scaling and non-Fermi liquid behavior. To tap into the full potential of the model, it is desirable to have a suitable control parameter that allows for accessing all the renormalization group fixed points supported by the model. Here, we utilize the large-S limit of the model [3] (where S is the spin size in the SU(2) symmetric model) to systematically access the fixed points and determine the quantum critical phenomena arising in their vicinity. Our results provide new insights into the quantum criticality in spin-isotropic heavy-fermion metals as well as in doped Mott-Hubbard systems.

[1] H. Hu, L. Chen, Q. Si, Nat. Phys, in press (2024); Q. Si et al., Nature 413, 804 (2001).

[2] S. Paschen and Q. Si, Nat. Rev. Phys. 9 (2021); S. Kirchner et al., Rev. Mod. Phys. 92, 011002 (2020).

[3] H. Hu et al., arXiv:2207.08744.