Phase diagram of pyrochlore iridates: all-in-all-out magnetic ordering and non-Fermi liquid properties

TL;DR

This paper investigates the phase diagram and magnetic properties of the pyrochlore iridate Y2Ir2O7 using first-principles calculations, revealing all-in-all-out magnetic order and non-Fermi liquid behavior due to strong correlations and flat bands.

Contribution

It provides a comprehensive phase diagram of Y2Ir2O7 with insights into magnetic ordering and non-Fermi liquid properties using LDA+DMFT methods, highlighting the importance of a three-band model.

Findings

All-in-all-out magnetic insulating phase is stable at realistic Coulomb U.

Strong inter-band correlations and band narrowing in the paramagnetic phase.

Non-Fermi liquid behavior in doped systems due to flat bands and quasi-spin moments.

Abstract

We study the prototype 5d pyrochlore iridate Y2Ir2O7 from first principles using the local density approximation and dynamical mean-field theory (LDA+DMFT). We map out the phase diagram in the space of temperature, onsite Coulomb repulsion U, and filling. Consistent with experiments, we find that an all-in-all-out ordered insulating phase is stable for realistic values of U. The trigonal crystal field enhances the magnetic moments of the jeff=1/2 doublet, and strong inter-band correlations are induced by the Coulomb interaction, which indicates that a three-band description is important. We demonstrate a substantial band narrowing in the paramagnetic metallic phase and non-Fermi liquid behavior in the electron/hole doped system originating from long-lived quasi-spin moments induced by nearly flat bands.