Strange metallicity develops near the quantum critical points in various strongly correlated material [1]. An especially important problem is how a loss of quasiparticle influences the quantum critical state. Heavy fermion systems serve as an ideal platform to study this issue [2]. In this work [3], we realize a continuous tuning from the conventional spin-density-wave (SDW) type quantum critical state to the Kondo destruction type of quantum critical state where the quasiparticle is completely lost. We found that for a Kondo lattice system, the bound of the Landau quantum criticality is considerably suppressed due to the competition between the RKKY and Kondo interactions. Therefore, a large dynamical range exists for Kondo-destruction type of quantum critical fluctuations. Our results provide the understanding of the quantum critical behavior observed in CeCu2Si2 and related heavy fermion systems. We also discuss the influence on the unconventional superconductivity from the loss of quasiparticle [4].

 

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

 

[2] H. Hu, L. Chen, Q. Si, arXiv:2210.14183; Q. Si et al, Nature 413, 804 (2001)

 

[3] L. Chen, Y. Wang, H. Hu, A. Cai, Q. Si, unpublished (2023).             

 

[4] H. Hu et al., arXiv:2109.13224