Topological states in pyrochlore iridates: long-range anisotropy strongly competing with spin-orbit interaction

Abstract

In the search for topological phases in correlated electron systems, iridium-based pyrochlores A2Ir2O7 -- materials with 5d transition-metal ions -- provide fertile grounds. Several novel topological states have been predicted but the actual realization of such states is believed to critically depend on the strength of local potentials arising from distortions of IrO6-cages. We test this hypothesis by measuring with resonant x-ray scattering the electronic level splittings in the A= Y, Eu systems, which we show to agree very well with ab initio electronic structure calculations. We find, however, that not distortions of IrO6-octahedra are the primary source for quenching the spin-orbit interaction, but strong long-range lattice anisotropies, which inevitably break the local cubic symmetry and will thereby be decisive in determining the system's topological ground state.

5 pages, 2 figures

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• Optical evidence for a Weyl semimetal state in pyrochlore Eu2Ir2O7
• Spin-orbit-entangled electronic phases in 4$d$ and 5$d$ transition-metal compounds
• Metal-insulator transition and topological properties of pyrochlore iridates
• All-in all-out magnetic order and propagating spin-waves in Sm2Ir2O7
• Mixing of $t_{2g}$-$e_g$ orbitals in 4d and 5d transition metal oxides
• Phase diagram of pyrochlore iridates: all-in-all-out magnetic ordering and non-Fermi liquid properties
• Emergent excitation at the magnetic metal-insulator transition in the pyrochlore osmate Cd2Os2O7
• CaIrO3: a Spin-Orbit Mott Insulator Beyond the jeff = 1/2 Ground State
• Determination of Hund's coupling in 5d Oxides using Resonant Inelastic X-ray Scattering
• Orbital reconstruction in nonpolar tetravalent transition-metal oxide layers
• Successive Symmetry Breaking in a Jeff = 3/2 Quartet in the Spin-Orbit Coupled Insulator Ba2MgReO6
• Anisotropy tuned magnetic order in pyrochlore iridates
• X-ray scattering study of pyrochlore iridates: crystal structure, electronic and magnetic excitations
• Pressure-driven collapse of the relativistic electronic ground state in a honeycomb iridate
• Epitaxial thin films of pyrochlore iridate Bi_{2+x}Ir_{2-y}O_{7-delta}: structure, defects and transport properties
• Revisiting the Kitaev material candidacy of Ir4+ double perovskite iridates
• Perspective: Strongly correlated and topological states in [111] grown transition metal oxide thin films and heterostructures
• Strong magnetic frustration and anti-site disorder causing spin-glass behavior in honeycomb Li2RhO3
• Covalency and vibronic couplings make a nonmagnetic j=3/2 ion magnetic
• Covalency-driven collapse of strong spin-orbit coupling in face-sharing iridium octahedra
• Long-range interactions in the effective low energy Hamiltonian of Sr2IrO4: a core level resonant inelastic x-ray scattering study
• Heavy-mass magnetic modes in pyrochlore iridates due to dominant Dzyaloshinskii-Moriya interaction
• Almost pure $J_{\mathrm{eff}}=1/2$ Mott state of In${}_2$Ir${}_2$O${}_7$ in the limit of reduced inter-site hopping
• Crystal field splitting in Sr${}_{n+1}$Ir${}_n$O${}_{3n+1}$ ($n$ = 1, 2) iridates probed by x-ray Raman spectroscopy
• Spin-phonon coupling in hole-doped pyrochlore iridates Y${}_2$(Ir${}_{1-x}$Ru${}_x$)${}_2$O${}_7$: A Raman scattering study
• Magnetic and transport properties in pyrochlore iridates (Y${}_{1-x}$Pr${}_x$)${}_2$Ir${}_2$O${}_7$: The role of $f$-$d$ exchange interaction and $d$-$p$ orbital hybridization
• Anisotropic interactions opposing magnetocrystalline anisotropy in Sr${}_3$NiIrO${}_6$
• First-principles studies of spin-orbital physics in pyrochlore oxides
• Resonant inelastic x-ray scattering spectra in the hyperhoneycomb iridate $\beta$-Li${}_2$IrO${}_3$: First principles calculations
• Evolution of structure and magnetism across the metal-insulator transition in the pyrochlore iridate $($Nd${}_{1-x}$Ca${}_x{)}_2$Ir${}_2$O${}_7$
• Magnetic excitations in hole-doped Sr2IrO4: A comparison with electron-doped cuprates
• Emergence of weak pyrochlore phase and signature of field induced spin ice ground state in Dy${}_{2-x}$La${}_x$Zr${}_2$O${}_7$; x = 0, 0.15, 0.3
• Thermal conductivity of local moment models with strong spin-orbit coupling
• Nonmagnetic substitution in pyrochlore iridate Y${}_2$(Ir${}_{1-x}$Ti${}_x$)${}_2$O${}_7$: Structure, magnetism and electronic properties
• Anisotropic antiferromagnetic order in spin-orbit coupled trigonal lattice Ca2Sr2IrO6
• Selective probing of magnetic order on Tb and Ir sites in stuffed Tb${}_{2+x}$Ir${}_{2-x}$O${}_{7-y}$ using resonant X-ray scattering
• On the electronic ground state of two non-magnetic pentavalent honeycomb iridates
• Traversing the pyrochlore stability diagram; microwave-assisted synthesis and discovery of mixed B-site Ln${}_2$InSbO${}_7$ family
• Electron quasi-itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetism
• Metal-insulator transitions in pyrochlore oxides
• Possibility of an unconventional spin state of Ir${}^{4+}$ in Ba${}_{21}$Ir${}_9$O${}_{43}$ single crystal
• Formation of orbital molecules on a pyrochlore lattice induced by A-O bond covalency