Emergent excitation at the magnetic metal-insulator transition in the pyrochlore osmate Cd2Os2O7

Abstract

The rich physics manifested by 5d oxides falls outside the Mott-Hubbard paradigm used to successfully explain the electronic and magnetic properties of 3d oxides. Much consideration has been given to the extent to which strong spin-orbit coupling (SOC), in the limit of increased bandwidth and reduced electron correlation, drives the formation of novel electronic states, as manifested through the existence of metal-insulator transitions (MITs). SOC is believed to play a dominant role in 5d5 systems such as iridates (Ir4+), undergoing MITs which may or may not be intimately connected to magnetic order, with pyrochlore and perovksite systems being examples of the former and latter, respectively. However, the role of SOC for other 5d configurations is less clear. For example, 5d3 (e.g Os5+) systems are expected to have an orbital singlet and consequently a reduced effect of SOC in the groundstate. The pyrochlore osmate Cd2Os2O7 nonetheless exhibits a MIT intimately entwined with magnetic order with phenomena similar to pyrochlore iridates. Here we report the first resonant inelastic X-ray scattering (RIXS) measurements on an osmium compound, allowing us to determine the salient electronic and magnetic energy scales controlling the MIT in Cd2Os2O7, which we benchmark against detailed quantum chemistry calculations. In particular, we reveal the emergence at the MIT of a magnetic excitation corresponding to a superposition of multiple spin-flip processes from an Ising-like all-in/all-out magnetic groundstate. We discuss our results with respect to the role of SOC in magnetically mediated MITs in 5d systems

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Cited by in corpus (38)

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• Ultrafast dynamics of spin and orbital correlations in quantum materials: an energy- and momentum-resolved perspective
• Spin-orbit coupled systems in the "atomic" limit: rhenates, osmates, iridates
• NaSrMn2F7, NaCaFe2F7, and NaSrFe2F7: novel single crystal pyrochlore antiferromagnets
• Dispersive Magnetic and Electronic Excitations in Iridate Perovskites Probed with Oxygen $K$-Edge Resonant Inelastic X-ray Scattering
• Strongly Gapped Spin-Wave Excitation in the Insulating Phase of NaOsO3
• Topological Properties and Functionalities in Oxide Thin Films and Interfaces
• Origin of magnetic excitation gap in double perovskite Sr${}_2$FeOsO${}_6$
• Direct detection of dimer orbitals in Ba${}_5$AlIr${}_2$O${}_{11}$
• Crystal structure and the magnetic properties of the 5d transition metal oxide AOsO4 (A = K, Rb, Cs)
• Magnetic excitations in a three-orbital model for the strongly spin-orbit coupled iridates: Effect of mixing between the J=1/2 and 3/2 sectors
• Osmates on the verge of a Hund's-Mott transition: The different fates of NaOsO${}_3$ and LiOsO${}_3$
• Interplay of spin-orbit coupling and hybridization in Ca3LiOsO6 and Ca3LiRuO6
• Crossover from itinerant to localized magnetic excitations through the metal-insulator transition in NaOsO${}_{\text{3}}$
• Nonlinear Magnetoelectric Effect under Magnetic Octupole Order: Its Application to a $d$-Wave Altermagnet and a Pyrochlore Lattice with All-In/All-Out Magnetic Order
• Coexistence of metallic and nonmetallic properties in the pyrochlore Lu${}_2$Rh${}_2$O${}_7$
• Resolving the nature of electronic excitations in resonant inelastic x-ray scattering
• First-principles studies of spin-orbital physics in pyrochlore oxides
• Strongly-coupled quantum critical point in an all-in-all-out antiferromagnet
• Spin-orbit coupling effects on spin-phonon coupling in Cd2Os2O7
• Noncollinear DFT+$U$ and Hubbard parameters with fully-relativistic ultrasoft pseudopotentials
• Evidence for $J_{\mathrm{eff}}=0$ ground state and defect-induced spin glass behaviour in the pyrochlore osmate Y${}_2$Os${}_2$O${}_7$
• Possible origin of the absence of magnetic order in LiOsO${}_3$: Spin-orbit coupling controlled ground state
• Spin-orbit coupling in a half-filled $t_{2g}$ shell: the case of $5d^3$ K${}_2$ReCl${}_6$
• Magnetically induced metal-insulator transition in Pb2CaOsO6
• Strain Induced Slater Transition in Polar Metal LiOsO${}_3$
• Spin and orbital dynamics through the metal-to-insulator transition in Cd${}_2$Os${}_2$O${}_7$ probed with high-resolution RIXS
• Spin-orbit coupling induced magnetic anisotropy and large spin wave gap in $\mathrm{NaOs}{\mathrm{O}}_3$
• Pyrochlore Oxide Hg2Os2O7 on Verge of Metal-Insulator Boundary
• Ultrafast dynamics in the Lifshitz-type 5$d$ pyrochlore antiferromagnet Cd${}_2$Os${}_2$O${}_7$
• Coupled Spin-Charge-Phonon Fluctuation in the All-In/All-Out Antiferromagnet Cd${}_2$Os${}_2$O${}_7$
• Exploring itinerant states in divalent hexaborides using rare-earth $L$ edge resonant inelastic X-ray scattering
• Anomalous Fermi pockets on Hund's metal surface of Sr2RuO4 induced by the correlation-enhanced spin-orbit coupling
• Indirect K-edge bimagnon resonant inelastic X-ray scattering spectrum of $\alpha$-FeTe
• Interaction-driven spin-orbit effects and Chern insulating phases in corundum-based $4d$ and $5d$ oxide honeycomb lattices
• Spin-Orbit Coupling-Driven Chirality Switching of Spin Waves in Altermagnets