Lattice-Tuned Magnetism of Ru4+(4d4) Ions in Single-Crystals of the Layered Honeycomb Ruthenates: Li2RuO3 and Na2RuO3

TL;DR

This study synthesizes and characterizes single-crystal layered honeycomb ruthenates Na2RuO3 and Li2RuO3, revealing how lattice distortions influence their magnetic ground states and uncovering a new correlation between structure and magnetism.

Contribution

It provides new insights into the relationship between lattice distortions and magnetic states in layered honeycomb ruthenates, with detailed synthesis and phase diagram analysis.

Findings

Na2RuO3 orders antiferromagnetically at 30 K

Li2RuO3 hosts a well-defined magnetic state unlike polycrystalline samples

A phase diagram links magnetic ground states to basal-plane distortions

Abstract

We synthesize and study single crystals of the layered honeycomb lattice Mott insulators Na2RuO3 and Li2RuO3 with magnetic Ru4+(4d4) ions. The newly found Na2RuO3 features a nearly ideal honeycomb lattice and orders antiferromagnetically at 30 K. Single-crystals of Li2RuO3 adopt a honeycomb lattice with either C2/m or more distorted P21/m below 300 K, depending on detailed synthesis conditions. We find that Li2RuO3 in both structures hosts a well-defined magnetic state, in contrast to the singlet ground state found in polycrystalline Li2RuO3. A phase diagram generated based on our results uncovers a new, direct correlation between the magnetic ground state and basal-plane distortions in the honeycomb ruthenates.