Quantum criticality of a quantum nonlinear sigma model with Kondo coupling: a renormalization group study

Quantum criticality has been an active research topic in condensed matter physics, with a lot of effort being made into the heavy fermion material in which local moments are coupled with itinerant electrons through Kondo coupling [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 of such systems [2]. Here we approach the problem from the magnetically ordered side, using a quantum non-linear sigma model with an additional coupling to itinerant fermions [3]. 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 criticality. Our results shed new light on the global phase diagram of the heavy fermion systems.

References:
[1] Q. Si and S. Paschen, “Quantum phase transitions in heavy fermion metals and Kondo insulators”, Phys. Status Solidi B 50, 425 (2013).
[2] S.Yamamoto and Q.Si, “ Renormalization group for mixed fermion-boson system”, Phys. Rev. B81, 205106 (2010).
[3] S.Yamamoto and Q.Si, “Fermi surface and antiferromagnetism in the Kondo lattice: an asymptotically exact solution in d > 1 dimensions”, Phys. Rev. Lett. 99, 016401 (2007).