Quantum Criticality of Kondo Lattice Model: A Renormalization Group Study via Quantum non-Linear Sigma Model**

Quantum criticality has been an active research topic in condensed matter physics, with major efforts being devoted to the heavy fermion metals [1]. From a theoretical perspective, the interplay between different kinds of degrees of freedom makes it challenging to develop a unified framework to study the quantum criticality. Here we approach the problem from the magnetically ordered side, and represent the Kondo lattice model using a quantum non-linear sigma model with an additional coupling to itinerant fermions. By treating the renormalization of the bosonic and fermionic degrees of freedom on an equal footing, we analyze the effect of the Kondo coupling on the quantum criticality. Our results shed new light on the global phase diagram of the heavy fermion systems [2] and, especially, the behavior of frustrated Kondo lattice [3,4].

[1] S. Paschen & Q. Si, Nat. Rev. Phys. (arXiv:2009.03602); S. Kirchner et al, Rev. Mod. Phys. 92, 011002 (2020); Q. Si et al., Nature 413, 804 (2001).
[2] Q. Si, Physica B378, 23 (2006); Phys. Status Solidi B 247, 476 (2010).
[3] H. Zhao et al, Nat. Phys. 15, 1261 (2019).
[4] M. Kavai et al, arXiv:2006.07424.