Predominance of the Kitaev interaction in a three-dimensional honeycomb iridate: from ab-initio to spin model

TL;DR

This study combines ab-initio calculations and spin modeling to show that the 3D hyperhoneycomb iridate $eta$-Li$_2$IrO$_3$ is dominated by Kitaev interactions, making it a promising candidate for realizing a quantum spin liquid.

Contribution

The paper demonstrates that $eta$-Li$_2$IrO$_3$ has a dominant Kitaev interaction based on combined ab-initio and spin model analysis, advancing understanding of potential quantum spin liquid materials.

Findings

Kitaev interaction dominates the spin model of $eta$-Li$_2$IrO$_3$

Electronic structure accurately captured by $j_{eff}=1/2$ basis

Material's magnetic order consistent with theoretical predictions

Abstract

The recently discovered three-dimensional hyperhoneycomb iridate, $\beta$-Li$_2$IrO$_3$, has raised hopes for the realization of dominant Kitaev interaction between spin-orbit entangled local moments due to its near-ideal lattice structure. If true, this material may lie close to the sought-after quantum spin liquid phase in three dimensions. Utilizing ab-initio electronic structure calculations, we first show that the spin-orbit entangled basis, $j_{\rm eff}$=1/2, correctly captures the low energy electronic structure. The effective spin model derived in the strong coupling limit supplemented by the ab-initio results is shown to be dominated by the Kitaev interaction. We demonstrated that the possible range of parameters is consistent with a non-coplanar spiral magnetic order found in a recent experiment. All of these analyses suggest that $\beta$-Li$_2$IrO$_3$ may be the closest among known materials to the Kitaev spin liquid regime.