Interplay between strong correlations and magnetic field in the symmetric periodic Anderson model

TL;DR

This paper investigates how magnetic fields influence the electronic properties of Kondo insulators within the symmetric periodic Anderson model, revealing a universal scaling behavior and a field-induced insulator-metal transition.

Contribution

It introduces a detailed theoretical analysis of magnetic field effects on the symmetric periodic Anderson model, highlighting the universal scaling and the nonlinear to linear hybridization gap dependence in different regimes.

Findings

Universal scaling of dynamics in the strongly correlated regime

Continuous insulator-metal transition with increasing magnetic field

Agreement with experimental data on YbB$_{12}$

Abstract

Magnetic field effects in Kondo insulators are studied theoretically, using a local moment approach to the periodic Anderson model within the framework of dynamical mean-field theory. Our main focus is on field-induced changes in single-particle dynamics and the associated hybridization gap in the density of states. Particular emphasis is given to the strongly correlated regime, where dynamics are found to exhibit universal scaling in terms of a field-dependent low energy coherence scale. Although the bare applied field is globally uniform, the effective fields experienced by the conduction electrons and the $f$-electrons differ because of correlation effects. A continuous insulator-metal transition is found to occur on increasing the applied field, closure of the hybridization gap reflecting competition between Zeeman splitting and screening of the $f$-electron local moments. For intermediate interaction strengths the hybridization gap depends non-linearly on the applied field, while in strong coupling its field dependence is found to be linear. For the classic Kondo insulator YbB$_{12}$, good agreement is found upon direct comparison of the field evolution of the experimental transport gap with the theoretical hybridization gap in the density of states.