Kondo destruction and SDW_r quantum criticality in heavy fermion metals

Two types of quantum criticality have been extensively discussed in canonical heavy fermion metals [1]. The first type is the Kondo destruction, corresponding to a beyond-Landau quantum critical point, in which quasiparticles are lost everywhere on the Fermi surface [2]. The second type corresponds to a fluctuating spin-density-wave (SDW), which is within the Landau framework of order-parameter fluctuations. Here [3], using the EDMFT and CTQMC method, we systematically show that even for the second type, the upper cutoff of the Landau quantum criticality, E_{cr}, is considerably smaller than the bare Kondo scale, due to the dynamical competition between the RKKY and Kondo interactions. Thus, a large dynamical range exists for Kondo-destruction quantum critical fluctuations above E_{cr} [3]. Accordingly, we propose the notion of SDW_r quantum criticality for heavy fermion metals. We explain how our results provide long-overdue understanding of the quantum critical behavior observed in CeCu2Si2 and related heavy fermion systems.



[1] S. Paschen & Q. Si, Nat. Rev. Phys. 3, 9 (2021).



[2] Q. Si et al, Nature 413, 804 (2001); S. Kirchner et al, Rev. Mod. Phys. 92, 011002 (2020).



[3] L. Chen, H. Hu, A. Cai, Q. Si, unpublished (2022).