Localized-itinerant dichotomy and unconventional magnetism in SrRu${}_2$O${}_6$

Abstract

Electron correlations tend to generate local magnetic moments that usually order if the lattices are not too frustrated. The hexagonal compound SrRu${}_2$O${}_6$ has a relatively high Neel temperature but small local moments, which seem to be at odds with the nominal valence of Ru${}^{5+}$ in the $t_{2g}^3$ configuration. Here, we investigate the electronic property of SrRu${}_2$O${}_6$ using density functional theory (DFT) combined with dynamical-mean-field theory (DMFT). We find that the strong hybridization between Ru $d$ and O $p$ states results in a Ru valence that is closer to $+4$, leading to the small ordered moment $\sim 1.2{\mu }_B$. While this is consistent with a DFT prediction, correlation effects are found to play a significant role. The local moment per Ru site remains finite $\sim 2.3{\mu }_B$ in the whole temperature range investigated. Due to the lower symmetry, the $t_{2g}$ manifold is split and the quasiparticle weight is renormalized significantly in the $a_{1g}$ state, while the renormalization in $e_g^{\prime }$ states is about a factor of 2--3 weaker. Our theoretical Neel temperature $\sim 700$~K is in reasonable agreement with experimental observations. SrRu${}_2$O${}_6$ is a unique system in which localized and itinerant electrons coexist with the proximity to an orbitally-selective Mott transition within the $t_{2g}$ sector.

9 pages, 4 figures

References in corpus (12)

• Strong electronic correlations from Hund's coupling
• Quantum Monte Carlo Impurity Solver for Cluster DMFT and Electronic Structure Calculations in Adjustable Base
• Hybridization expansion impurity solver: General formulation and application to Kondo lattice and two-orbital models
• Orbital-Selective Mott transition out of band degeneracy lifting
• Plane-wave based electronic structure calculations for correlated materials using dynamical mean-field theory and projected local orbitals
• Nature of magnetic excitations in superconducting BaFe${}_{1.9}$Ni${}_{0.1}$As${}_2$
• Dichotomy between large local and small ordered magnetic moment in Iron-based superconductors
• Tetrahedral Magnetic Order and the Metal-Insulator Transition in the Pyrochlore Lattice of Cd2Os2O7
• Antiferromagnetism at T > 500 K in the Layered Hexagonal Ruthenate SrRu2O6
• Effective magnetic interactions in spin-orbit coupled $d^4$ Mott insulators
• High antiferromagnetic transition temperature of a honeycomb compound SrRu${}_2$O${}_6$
• Electronic structure and the origin of the high ordering temperature in SrRu2O6