J = 0 nonmagnetic insulating state in K${}_2$Os$X_6$ (X = F, Cl and Br)

Abstract

In $4d/5d$ transition-metal systems, many interesting physical properties arise from the interplay of bandwidth, electronic correlations, and spin-orbit interactions. Here, using {\it ab initio} density functional theory, we systematically study the double-perovskite-like system K${}_2$Os$X_6$ (X = F, Cl, and Br) with a $5d^4$ electronic configuration. Our main result is that the $J=0$ nonmagnetic insulating state develops in this system, induced by strong spin-orbital coupling. Specifically, the well-separated Os$X_6$ octahedra lead to the cubic crystal-field limit and result in dramatically decreasing hoppings in nearest neighbor Os-Os sites. In this case, the three degenerate $t_{2g}$ orbitals are reconstructed into two ``effective'' $j_{\mathrm{eff}}$ ($j_{\mathrm{eff}}=1/2$ and $j_{\mathrm{eff}}=3/2$ states) states separated by the strong SOC, opening a gap with four electrons occupying the $j_{\mathrm{eff}}=3/2$ orbitals. Furthermore, the hybridization between the Os $5d$ orbitals and the $X$ ($X$ = F, Cl, and Br) $p$ orbitals increases from F to Br, leading the electrons in K${}_2$OsF${}_6$ to be more localized than in K${}_2$OsCl${}_6$ and K${}_2$OsBr${}_6$, resulting in a smaller bandwidth for K${}_2$OsF${}_6$ than in the Cl- or Br- cases. Our results provide guidance to experimentalists and theorists working on this interesting family of osmium halides.

References in corpus (13)

• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Novel Jeff = 1/2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr2IrO4
• Possibility of Combining Ferroelectricity and Rashba-like spin splitting in Monolayers of 1T-type Transition-Metal Dichalcogenides MX2
• Neutron and ARPES Constraints on the Couplings of the Multiorbital Hubbard Model for the Pnictides
• Orbital-dependent singlet dimers and orbital-selective Peierls transitions in transition metal compounds
• Effective magnetic interactions in spin-orbit coupled $d^4$ Mott insulators
• J-freezing and Hund's rules in spin-orbit-coupled multiorbital Hubbard models
• Hopping induced ground-state magnetism in 6H perovskite iridates
• Density matrix renormalization group study of a three-orbital Hubbard model with spin-orbit coupling in one dimension
• Magnetic states of quasi-one-dimensional iron chalcogenide Ba${}_2$FeS${}_3$
• Strongly anisotropic electronic and magnetic structures in oxide dichlorides RuOCl${}_2$ and OsOCl${}_2$
• Magnetization dynamics fingerprints of an excitonic condensate $t_{2g}^4$ magnet

Cited by in corpus (2)

• Stability of the novel interorbital-hopping mechanism for ferromagnetism in multi-orbital Hubbard models
• Electronic excitations in $5d^4$ J=0 Os${}^{4+}$ halides studied by RIXS and optical spectroscopy