Field-induced phase transitions in a Kondo insulator

TL;DR

This paper investigates how magnetic fields influence phase transitions in Kondo insulators using the periodic Anderson model, revealing field-induced magnetic and metallic phases and their temperature dependencies.

Contribution

It provides a detailed phase diagram of a Kondo insulator under magnetic fields using dynamical mean field theory and quantum Monte Carlo simulations, highlighting new magnetic and metallic phases.

Findings

Magnetic field induces a transverse antiferromagnetic phase at low temperatures.

The antiferromagnetic transition temperature peaks when Zeeman energy matches the quasi-particle gap.

Electron mass peaks when the quasi-particle gap closes under a magnetic field.

Abstract

We study the magnetic-field effect on a Kondo insulator by exploiting the periodic Anderson model with the Zeeman term. The analysis using dynamical mean field theory combined with quantum Monte Carlo simulations determines the detailed phase diagram at finite temperatures. At low temperatures, the magnetic field drives the Kondo insulator to a transverse antiferromagnetic phase, which further enters a polarized metallic phase at higher fields. The antiferromagnetic transition temperature $T_c$ takes a maximum when the Zeeman energy is nearly equal to the quasi-particle gap. In the paramagnetic phase above $T_c$, we find that the electron mass gets largest around the field where the quasi-particle gap is closed. It is also shown that the induced moment of conduction electrons changes its direction from antiparallel to parallel to the field.