Non-local self energies in pyrochlore iridates from ab-initio TRILEX calculations, and their relevance for the Weyl semimetal phase

TL;DR

This study compares local and non-local correlation effects in pyrochlore iridates using ab-initio TRILEX calculations, revealing the potential for Weyl semimetal phases near the metal-insulator transition.

Contribution

It introduces a TRILEX approach incorporating non-local correlations for pyrochlore iridates based on ab-initio calculations, highlighting the emergence of Weyl semimetal phases.

Findings

TRILEX predicts a Weyl-semimetal regime near the metal-insulator transition.

Critical interaction values differ between single-site DMFT and TRILEX.

All-in/all-out magnetic ordering is confirmed in the antiferromagnetic phase.

Abstract

Motivated by recent experiments and computational results on pyrochlore iridates, we compare single-particle properties of Y2Ir2O7 obtained from single-site dynamical mean-field calculations with results within the TRILEX approximation, where the latter takes non-local correlations into account. Our calculations are all based on ab-initio calculations within density-functional theory, and take spin-orbit coupling into account. In order to make the treatment within TRILEX feasible, we first define a single-band jeff = 1/2 model, by comparing its spectral features within DMFT to a three-band model that includes both jeff = 1/2 and jeff = 3/2 orbitals. Our calculations show consistently a paramagnetic metallic phase at small interaction values, and an insulating antiferromagnetic phase at larger interaction values. The critical interactions, however, differ between single-site and TRILEX calculations. The antiferromagnetic phase shows the already predicted all-in/all-out magnetic ordering. Different to the single-site results, the TRILEX calculation gives also evidence for the Weyl-semimetal regime in the vicinity of the metal-insulator transition.