Correlated Dirac semimetal states in nonsymmorphic MIrO$_3$ (M=Sr, Ba and Ca)

TL;DR

This paper demonstrates the emergence of correlated Dirac semimetal states in nonsymmorphic iridium oxides, driven by electron correlations, spin-orbit coupling, and symmetry, revealing topological surface features and robust Dirac fermions.

Contribution

It introduces a theoretical framework combining DFT and DMFT to identify correlated DSM states in SrIrO$_3$, BaIrO$_3$, and CaIrO$_3$, highlighting the role of nonsymmorphic symmetries and strong interactions.

Findings

Dirac fermions are formed by $J_{eff}=1/2$ states with mass enhancement.

Nonsymmorphic symmetries induce topological surface bands and Fermi arcs.

Correlated DSM states are established in iridium oxides under strong interactions.

Abstract

Nonsymmorphic symmetries can give rise to Dirac semimetal (DSM) states. However, few studies have been conducted on DSMs in interacting systems. Here, we induce interacting DSM states in nonsymmorphic iridium oxides SrIrO$_3$, BaIrO$_3$ and CaIrO$_3$, and contend that the interaction of electron-electron correlations, strong spin-orbital coupling, and symmetry protection can drive robust and exotic DSM states. Based on the density functional theory combined with dynamical mean-field theory (DFT + DMFT), with the Coulomb interaction parameters computed through doubly screened Coulomb correction approach, we discover that the Dirac fermions are constituted by the strongly spin-orbital coupled $J_{\mathrm{eff}} = 1/2$ states resulting from $t_{2g}$ orbits of Ir, with significant mass enhancement. Moreover, the nonsymmorphic symmetries induce topological surface bands and Fermi arcs on the (001) surface, which are well separated from bulk states. Our findings establish nonsymmorphic iridium oxides as correlated DSMs under strong electron-electron and spin-orbital interactions.