Computational Design of Axion Insulators Based on 5d Spinels Compounds

TL;DR

This paper uses density functional calculations to propose new 5d spinel compounds with exotic electronic and magnetic properties, including axion insulator behavior, ferromagnetism, and potential for various electronic phases.

Contribution

It introduces hypothetical Osmium-based spinel compounds with predicted exotic properties, expanding the design space for axion insulators.

Findings

CaOs2O4 and SrOs2O4 can be stabilized in spinel structure.

Predicted properties include ferromagnetism and orbital magnetoelectric effects.

Existence of electronic phases like 3D Dirac metal and Mott insulator.

Abstract

Based on density functional calculation with LDA+U method, we propose that hypothetical Osmium compounds such as CaOs2O4 and SrOs2O4 can be stabilized in the geometrically frustrated spinel crystal structure. They also show some exotic electronic and magnetic properties in a reasonable range of on-site Coulomb correlation U such as ferromagnetism and orbital magnetoelectric effect characteristic to Axion electrodynamics. Other electronic phases including 3D Dirac metal and Mott insulator exist and would make perspective 5d spinels ideal for applications.