Covalent bonds against magnetism in transition metal compounds

Abstract

Magnetism in transition metal compounds is usually considered starting from a description of isolated ions, as exact as possible, and treating their (exchange) interaction at a later stage. We show that this standard approach may break down in many cases, especially in $4d$ and $5d$ compounds. We argue that there is an important intersite effect -- an orbital-selective formation of covalent metal-metal bonds, which leads to an "exclusion" of corresponding electrons from the magnetic subsystem, and thus strongly affects magnetic properties of the system. This effect is especially prominent for noninteger electron number, when it results in suppression of the famous double exchange, the main mechanism of ferromagnetism in transition metal compounds. We study this novel mechanism analytically and numerically and show that it explains magnetic properties of not only several $4d-5d$ materials, including Nb${}_2$O${}_2$F${}_3$ and Ba${}_5$AlIr${}_2$O${}_{11}$, but can also be operative in $3d$ transition metal oxides, e.g. in CrO${}_2$ under pressure. We also discuss the role of spin-orbit coupling on the competition between covalency and magnetism. Our results demonstrate that strong intersite coupling may invalidate the standard single-site starting point for considering magnetism, and can lead to a qualitatively new behaviour.

References in corpus (11)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Novel Jeff = 1/2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr2IrO4
• $\alpha$-RuCl3: a Spin-Orbit Assisted Mott Insulator on a Honeycomb Lattice
• Magnetic order in $\alpha$-RuCl${}_3$: a honeycomb lattice quantum magnet with strong spin-orbit coupling
• Possible valence-bond condensation in the frustrated cluster magnet LiZn2Mo3O8
• Spin--orbital interaction for face-sharing octahedra: Realization of a highly symmetric SU(4) model
• Orbital-dependent singlet dimers and orbital-selective Peierls transitions in transition metal compounds
• Lattice-Tuned Magnetism of Ru4+(4d4) Ions in Single-Crystals of the Layered Honeycomb Ruthenates: Li2RuO3 and Na2RuO3
• Double Exchange Ferromagnetism in the Peierls Insulator State
• Generalized Hund's rule for two-atom systems
• Magnetism and charge ordering in high- and low-temperature phases of Nb2O2F3

Cited by in corpus (52)

• Models and Materials for Generalized Kitaev Magnetism
• Orbital effects in solids: basics, recent progress and opportunities
• Orbital physics in transition metal compounds: new trends
• Electronic structure, dimer physics, orbital-selective behavior, and magnetic tendencies in the bilayer nickelate superconductor La${}_3$Ni${}_2$O${}_7$ under pressure
• Hexagonal Perovskites as Quantum Materials
• Pressure-induced dimerization and valence bond crystal formation in the Kitaev-Heisenberg magnet alpha-RuCl3
• Mott metal-insulator transitions in pressurized layered trichalcogenides
• Local orbital degeneracy lifting as a precursor to an orbital-selective Peierls transition
• Resonant inelastic x-ray incarnation of Young's double-slit experiment
• Persistent low-temperature spin dynamics in the mixed-valence iridate Ba${}_3$InIr${}_2$O${}_9$
• Frustrated spin-1/2 molecular magnetism in the mixed-valence antiferromagnets Ba3MRu2O9 (M = In, Y, Lu)
• Featureless adaptive optimization accelerates functional electronic materials design
• The role of defects in the metal-insulator transition in VO${}_2$ and V${}_2$O${}_3$
• Orbital and spin order in spin-orbit coupled $d^1$ and $d^2$ double perovskites
• Orbital-selective Peierls phase in the metallic dimerized chain MoOCl${}_2$
• A Geometrically Frustrated Trimer-Based Mott Insulator
• Modulating Super-Exchange Strength to Achieve Robust Ferromagnetic Couplings in Two-Dimensional Semiconductors
• Covalency-driven collapse of strong spin-orbit coupling in face-sharing iridium octahedra
• Structural evolution and skyrmionic phase diagram of the lacunar spinel GaMo${}_4$Se${}_8$
• Suppression of magnetism under pressure in FeS: a LDA+DMFT study
• Mapping Skyrmion Stability in Uniaxial Lacunar Spinel Magnets from First-Principles
• Direct detection of dimer orbitals in Ba${}_5$AlIr${}_2$O${}_{11}$
• Nearly itinerant electronic groundstate in the intercalated honeycomb iridate Ag${}_3$LiIr${}_2$O${}_6$
• Covalency a Pathway for Achieving High Magnetisation in $TMF{e}_2{O}_4$ Compounds
• Realization of the orbital-selective Mott state at the molecular level in Ba${}_3$LaRu${}_2$O${}_9$
• Electronic structure and properties of lithium-rich complex oxides
• Orbital-selective confinement effect of Ru $4d$ orbitals in SrRuO${}_3$ ultrathin film
• Spectroscopic signatures of molecular orbitals on a honeycomb lattice
• Three-site transition-metal clusters: going from localized electrons to molecular orbitals
• Quasimolecular electronic structure of the spin-liquid candidate Ba${}_3$InIr${}_2$O${}_9$
• Ordering of Fe and Zn ions and magnetic properties of FeZnMo3O8
• RIXS interferometry and the role of disorder in the quantum magnet Ba${}_3$Ti${}_{3-x}$Ir${}_x$O${}_9$
• Nuclear and magnetic spin structure of the antiferromagnetic triangular lattice compound LiCrTe${}_2$ investigated by ${\mu }^{+}$SR as well as neutron and X-ray diffraction
• The Duel of Magnetic Interactions & Structural Instabilities: Itinerant Frustration in the Triangular Lattice Compound LiCrSe${}_2$
• Lattice dynamics and structural transition of the hyperhoneycomb iridate $\beta$-Li${}_2$IrO${}_3$ investigated by high-pressure Raman scattering
• Soft and anisotropic local moments in 4$d$ and 5$d$ mixed-valence M${}_2$O${}_9$ dimers
• Raman spectroscopy of the low dimensional antiferromagnet with large Neel temperature SrRu2O6
• Electronic correlations and competing orders in multiorbital dimers: a cluster DMFT study
• Spin-orbital correlations from complex orbital order in MgV${}_2$O${}_4$
• Frustration induced non-Curie-Weiss paramagnetism in La3Ir3O11: a fractional-valence-state iridate
• Magnetism and charge ordering in high- and low-temperature phases of Nb2O2F3
• Charge ordering in Ir dimers in the ground state of Ba${}_5$AlIr${}_2$O${}_{11}$
• Magnetic ground state of the dimer-based hexagonal perovskite Ba${}_3$ZnRu${}_2$O${}_9$
• Dimerization in honeycomb Na2RuO3 under pressure: a DFT study
• Multipeak quasielastic light scattering and high-frequency electronic excitations in honeycomb Li${}_2$RuO${}_3$
• Coexisting Z-type charge and bond order in metallic NaRu${}_2$O${}_4$
• Pressure-induced transition from Jeff=1/2 to S=1/2 states in CuAl2O4
• An \textit{ab initio} study of magnetic structure transitions of FePS${}_3$ under high pressure
• Unusual ferrimagnetic ground state in rhenium ferrite
• Orbital-slective behaviour in cubanite CuFe2S3
• Doping effects on the valence bond solid of Li${}_2$RuO${}_3$ with Mn substitution
• Response to comment on "Spin-lattice coupling and the emergence of the trimerized phase in the $S=1$ kagome antiferromagnet Na${}_2$Ti${}_3$Cl${}_8$", Phys. Rev. Lett. 124, 167203 (2020)