Defect control in the Heisenberg-Kitaev candidate material NaRuO$_2$

TL;DR

This study explores the synthesis challenges of NaRuO₂, revealing defect formation and solid-solution behavior, and emphasizes the importance of precise stoichiometry control for accurate physical property analysis.

Contribution

We demonstrate defect formation in NaRuO₂, establish a Na$_{3+x}$Ru$_{3-x}$O$_6$ solid solution, and show how stoichiometry affects magnetic and electronic properties.

Findings

NaRuO₂ tends to form Ru defects during synthesis.

A full solid solution exists between NaRuO₂ and Na₂RuO₃.

Stoichiometry significantly influences magnetic and transport properties.

Abstract

The combination of geometric frustration, extended hopping, spin-orbit coupling, and a disordered magnetic ground state make NaRuO$_{2}$ an attractive Heisenberg-Kitaev candidate material. Historically, NaRuO$_2$ has been a challenging material to produce, even in polycrystalline form. Here we present synthetic efforts that identify a propensity for Na$_\text{Ru}$ defects to form in NaRuO$_2$, revealing a full solid-solution between NaRuO$_{2}$ and disordered Na$_2$RuO$_3$. We report the synthesis of alloys along the Na$_{3+x}$Ru$_{3-x}$O$_6$ solid solution and characterize changes in the bulk magnetization and electron transport as a function of Na-loading. Our results highlight the importance of stoichiometry control in NaRuO$_{2}$ when investigating and interpreting this material's physical properties.