Loop Current and Orbital Magnetism in Pyrite-Type $Ir_{3}Ch_{8}$ ($Ch=Se,Te$)

TL;DR

This paper investigates the electronic structure and magnetic properties of the pyrite-type $Ir_{3}Ch_{8}$ compound, revealing a loop current ground state linked to strong diamagnetism and proposing its fluctuations as a potential superconductivity mechanism.

Contribution

It introduces a three-band tight-binding model for $Ir_{3}Ch_{8}$ and identifies a loop current ground state as key to its magnetic behavior and possible superconductivity.

Findings

Presence of a loop current ground state.

Highly anisotropic strong diamagnetism.

Loop current fluctuations as a pairing mechanism.

Abstract

We study the parent compound of the pyrite-type $Ir_{x}Ch_{2}$ iridium chalcogenide superconductors, $Ir_{0.75}Ch_{2}$ (or $Ir_{3}Ch_{8}$). While the lattice structure of the material is rather complicated, we show that the electron physics near the Fermi surface (FS) can be described by a three-band tight-binding model. We find that the material possesses a loop current ground state which is responsible for the highly anisotropic strong diamagnetism observed in experiments. The fluctuations of this loop current state can be a possible pairing mechanism for superconductivity.