Spin-orbit coupling, strong correlation, and insulator-metal transitions: the J${}_{\mathrm{eff}}$ =3\2 ferromagnetic Mott insulator Ba${}_2$NaOsO${}_6$

Abstract

The double perovskite Ba${}_2$NaOsO${}_6$ (BNOO), an exotic example of a very high oxidation state (heptavalent) osmium $d^1$ compound and also uncommon by being a ferromagnetic Mott insulator without Jahn-Teller (JT) distortion, is modeled using the density functional theory (DFT) hybrid functional based exact exchange for correlated electrons (oeeHyb) method and including spin-orbit coupling (SOC). The experimentally observed narrow gap ferromagnetic insulating ground state is obtained, with easy axis along [110] in accord with experiment, providing support that this approach provides a realistic method for studying this system. The predicted spin density for [110] spin orientation is nearly cubic (unlike for other directions), providing an explanation for the absence of JT distortion. An orbital moment of -0.4${\mu }_B$ strongly compensates the +0.5${\mu }_B$ spin moment on Os, leaving a strongly compensated moment more in line with experiment. Remarkably, the net moment lies primarily on the oxygen ions. An insulator-metal transition by rotating the magnetization direction with an external field under moderate pressure is predicted as one consequence of strong SOC, and metallization under moderate pressure is predicted. Comparison is made with the isostructural, isovalent insulator Ba${}_2$LiOsO${}_6$ which however orders antiferromagnetically.

10 pages, 6 figues

References in corpus (9)

• 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
• Bandwidth-Controlled Insulator-Metal Transition and Correlated Metallic State in 5$d$ Transition Metal Oxides Sr${}_{n+1}$Ir${}_n$O${}_{3n+1}$ ($n$=1, 2, and $\infty$)
• Anisotropy and Magnetism in the LSDA+U Method
• Ferromagnetism in the Mott insulator Ba2NaOsO6
• Cooperative Effect of Electron Correlation and Spin-Orbit Coupling on the Electronic and Magnetic Properties of Ba2NaOsO6
• Orbital-quenching-induced magnetism in Ba_2NaOsO_6
• Structural and Correlation Effects in the Itinerant Insulating Antiferromagnetic Perovskite NaOsO3
• Unquenched $e_g^1$ orbital moment in the Mott insulating antiferromagnet KOsO4

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• Covalency and vibronic couplings make a nonmagnetic j=3/2 ion magnetic
• Structural and metal-insulator transitions in rhenium based double perovskites via orbital ordering
• Phase transition preceding magnetic long-range order in the double perovskite Ba2NaOsO6
• Calculated g-factors of 5d double perovskites Ba2NaOsO6 and Ba2YOsO6
• Symmetry-protected Spinful Magnetic Weyl Nodal Loops and Multi-Weyl Nodes in $5d^n$ Cubic Double Perovskites $(n=1,2)$
• Doping-dependent bandwidth renormalization and spin-orbit coupling in (Sr${}_{1-x}$La${}_x$)${}_2$RhO${}_4$
• Sr4Os3O12- A Layered Osmate (V,VI) that is Magnetic close to Room Temperature