Self-consistent perturbational study of insulator-to-metal transition in Kondo insulators due to strong magnetic field

TL;DR

This study investigates how strong magnetic fields induce an insulator-to-metal transition in Kondo insulators using a self-consistent perturbation approach, revealing a first-order transition and magnetization jump.

Contribution

It introduces a self-consistent second-order perturbation method combined with local approximation to analyze magnetic field effects on Kondo insulators, providing new insights into the transition mechanism.

Findings

Energy gap closes under magnetic field leading to insulator-metal transition.

First order transition occurs at a critical magnetic field $H_c$.

Magnetization exhibits a jump at the transition point.

Abstract

In order to study the effects of strong magnetic field on Kondo insulators, we calculate magnetization curves and single-particle excitation spectra of the periodic Anderson model at half-filling under finite magnetic field by using the self-consistent second-order perturbation theory combined with the local approximation which becomes exact in the limit of infinite spatial dimensions. Without magnetic field, the system behaves as an insulator with an energy gap, describing the Kondo insulators. By applying magnetic field to f-electrons, we found that the energy gap closes and the first order transition from insulator to metal takes place at a critical field $H_c$. The magnetization curve shows a jump at $H_c$. These are consistent with our previous study in terms of the exact diagonalization. Relationship to the experiments on YbB$_{12}$ and some other Kondo insulators is discussed.