Emergence of electronic modes by doping Kondo insulators in the Kondo lattice and periodic Anderson models

TL;DR

This paper investigates how doping Kondo insulators in the Kondo lattice and periodic Anderson models leads to the emergence of electronic modes within the insulating gap, revealing interaction effects beyond mean-field approximations.

Contribution

It demonstrates the emergence of electronic modes due to doping in Kondo insulators, highlighting the role of strong correlations and spin-charge separation in the transition to metallic states.

Findings

Electronic modes appear in the insulating gap upon doping.

Emergence of high-energy electronic modes in the periodic Anderson model.

Interaction effects differ from conventional mean-field predictions.

Abstract

Heavy-fermion or Kondo lattice materials are considered to be typical strongly correlated systems, for which mean-field approximations have shown that the Coulomb interaction increases the effective mass and narrows the band gap. In this paper, to clarify interaction effects on the electronic excitation, the spectral function of the Kondo lattice and periodic Anderson models is studied around Kondo insulators in the strong-coupling regime, by using the non-Abelian dynamical density-matrix renormalization group method and perturbation theory. Upon doping a Kondo insulator, an electronic mode emerges in the Kondo insulating gap, exhibiting the momentum-shifted magnetic dispersion relation. Although the ground-state properties are similar to those of a doped band insulator, the emergence of the electronic mode reflecting spin-charge separation of the Kondo insulator is a crucial interaction effect that allows us to regard the Kondo-insulator--metal transition as a type of Mott transition. In addition, electronic modes emerge even in the high-energy regime by doping in the periodic Anderson model. These strong-correlation effects have not been expected in conventional mean-field approximations and would bring a different perspective on heavy-fermion or Kondo lattice systems.