Metallic ruthenium ilmenites: first-principles study of MgRuO${}_3$ and CdRuO${}_3$

Abstract

Ilmenites $AB$O${}_3$ provide a platform for electron correlation and magnetism on alternatively stacked honeycomb layers of edge-sharing $A$O${}_6$ or $B$O${}_6$ octahedra. When $A$ and $B$ are $3d$ transition metals, strong electron correlation makes the systems Mott insulators showing various magnetic properties, while when $B$ is Ir with $5d$ electrons, competition between electron correlation and spin-orbit coupling realizes a spin-orbital coupled Mott insulator as a potential candidate for quantum spin liquids. Here we theoretically investigate intermediate $4d$ ilmenites, $A$RuO${}_3$ with $A$=Mg and Cd, which were recently synthesized and shown to be metallic, unlike the $3d$ and $5d$ cases. By using first-principles calculations, we optimize the lattice structures and obtain the electronic band structures. We show that MgRuO${}_3$ exhibits strong dimerization on RuO${}_6$ honeycomb layers, leading to the formation of bonding and anti-bonding bands for one of three $t_{2g}$ orbitals; the lattice symmetry is lowered from $R\bar{3}$ to $P\bar{1}$, and the Fermi surfaces are composed of the other two $t_{2g}$ orbitals. In contrast, we find that CdRuO${}_3$ has a lattice structure close to $R\bar{3}$, and all three $t_{2g}$ orbitals contribute almost equally to the Fermi surfaces. Comparison of our results with other Ru honeycomb materials such as Li${}_2$RuO${}_3$ indicates that the metallic ruthenium ilmenites stand on a subtle balance among electron correlation, spin-orbit coupling, and electron-phonon coupling.

References in corpus (21)

• Advanced capabilities for materials modelling with Quantum ESPRESSO
• Kitaev-Heisenberg Model on Honeycomb Lattice: Possible Exotic Phases in Iridium Oxides $A_2$IrO${}_3$
• Kitaev quantum spin liquid - concept and materialization
• Relevance of the Heisenberg-Kitaev model for the honeycomb lattice iridates A_2IrO_3
• Models and Materials for Generalized Kitaev Magnetism
• Challenges in Design of Kitaev Materials: Magnetic Interactions from Competing Energy Scales
• Hunting Majorana Fermions in Kitaev Magnets
• Kitaev interactions between j=1/2 moments in honeycomb Na2IrO3 are large and ferromagnetic: insights from ab initio quantum chemistry calculations
• First-Principles Study of the Honeycomb-Lattice Iridates Na2IrO3 in the Presence of Strong Spin-Orbit Interaction and Electron Correlations
• Ab initio analysis of the tight-binding parameters and magnetic interactions in Na2IrO3
• New Type Phase Transition of Li2RuO3 with Honeycomb Structure
• Electric Toroidal Quadrupoles in Spin-Orbit Coupled Metal Cd${}_2$Re${}_2$O${}_7$
• Single crystal growth from separated educts and its application to lithium transition-metal oxides
• Pyrochlore Oxide Superconductor Cd2Re2O7 Revisited
• Classical dimers and dimerized superstructure in orbitally degenerate honeycomb antiferromagnet
• Magnetic ordering with an XY-like anisotropy in the honeycomb lattice iridates ZnIrO${}_3$ and MgIrO${}_3$ synthesized via a metathesis reaction
• Structural Transition of Li2RuO3 Induced by Molecular-Orbit Formation
• Strong antiferromagnetic interaction owing to a large trigonal distortion in the spin-orbit-coupled honeycomb lattice iridate CdIrO${}_3$
• Electronic and magnetic properties of iridium ilmenites $A$IrO${}_3$ ($A=$ Mg, Zn, and Mn)
• Magneto-structural coupling in ilmenite-type NiTiO${}_3$: a combined diffraction and dilatometry study
• Spin-orbit-coupled metal candidate PbRe2O6