Non-coplanar and counter-rotating incommensurate magnetic order stabilized by Kitaev interactions in $\gamma$-Li2IrO3

TL;DR

This study reveals that $ ext{γ}$-Li$_2$IrO$_3$ exhibits a complex incommensurate magnetic order driven by dominant Kitaev interactions, advancing understanding of Kitaev materials and their magnetic properties.

Contribution

The paper demonstrates that $ ext{γ}$-Li$_2$IrO$_3$ hosts a non-coplanar, counter-rotating incommensurate magnetic structure explained by a minimal Kitaev-Heisenberg model, confirming strong Kitaev interactions.

Findings

Complex incommensurate magnetic order observed

Non-coplanar and counter-rotating Ir moments identified

Kitaev interactions dominate the magnetic behavior

Abstract

Materials that realize Kitaev spin models with bond-dependent anisotropic interactions have long been searched for, as the resulting frustration effects are predicted to stabilize novel forms of magnetic order or quantum spin liquids. Here we explore the magnetism of $\gamma$-Li$_2$IrO$_3$, which has the topology of a 3D Kitaev lattice of inter-connected Ir honeycombs. Using resonant magnetic x-ray diffraction we find a complex, yet highly-symmetric incommensurate magnetic structure with non-coplanar and counter-rotating Ir moments. We propose a minimal Kitaev-Heisenberg Hamiltonian that naturally accounts for all key features of the observed magnetic structure. Our results provide strong evidence that $\gamma$-Li$_2$IrO$_3$ realizes a spin Hamiltonian with dominant Kitaev interactions.