Orbital diamagnetic susceptibility in excitonic condensation phase

TL;DR

This paper investigates how excitonic condensation affects orbital diamagnetic susceptibility in different materials, revealing contrasting behaviors in semiconductors and semimetals, and compares theoretical results with experimental data on Ta2NiSe5.

Contribution

It introduces a mean-field approach to analyze orbital diamagnetic susceptibility in excitonic phases and applies it to real materials, providing new insights into their magnetic properties.

Findings

Excitonic condensation induces finite diamagnetic susceptibility in semiconductors.

In semimetals, excitonic condensation suppresses the normal phase susceptibility.

Theoretical calculations qualitatively match experimental susceptibility in Ta2NiSe5.

Abstract

We study the orbital diamagnetic susceptibility in excitonic condensation phase using the meanfield approximation for a two-band model defined on a square lattice. We find that, in semiconductors, the excitonic condensation acquires a finite diamagnetic susceptibility due to spontaneous hybridization between the valence and the conduction bands, whereas in semimetals, the diamagnetic susceptibility in the normal phase is suppressed by the excitonic condensation. We also study the orbital diamagnetic and Pauli paramagnetic susceptibilities of Ta2NiSe5 using a two-dimensional three-band model and find that the calculated temperature dependence of the magnetic susceptibility is in qualitative agreement with experiment.