Magnetic properties of a Kondo insulator with RKKY interaction: Extended dynamical mean field study

TL;DR

This study uses extended dynamical mean field theory to analyze how magnetic field and RKKY interactions influence the magnetic and electronic properties of a Kondo insulator, revealing a tendency to maintain the insulating gap near quantum criticality.

Contribution

It introduces an extended dynamical mean field approach to explore the interplay of RKKY interactions and magnetic fields in Kondo insulators, highlighting the stability of the insulating gap.

Findings

Magnetic field and RKKY interaction induce antiferromagnetic instability.

Enhanced transverse spin fluctuations near quantum critical point.

Kondo insulating gap persists up to large magnetic fields.

Abstract

We study the Kondo lattice model with the Heisenberg-type RKKY-exchange coupling among localized f-spins in the presence of a magnetic field. By means of an extended dynamical mean field theory combined with the non-crossing approximation, we investigate the one-particle spectral function and the dynamical spin correlation function in the Kondo insulating phase. It is shown that the magnetic field and the RKKY exchange interaction both cause the instability to the antiferromagnetic order with enhanced transverse spin fluctuations, which give rise to a strong renormalization of quasi-particles as the system approaches the quantum critical point. This leads to a tendency to retain the Kondo insulating gap up to rather large fields.