Magnetic excitation spectra in pyrochlore iridates

Abstract

Metal-insulator transitions in pyrochlore iridates (A2Ir2O7) are believed to occur due to subtle interplay of spin-orbit coupling, geometric frustration, and electron interactions. In particular, the nature of magnetic ordering of iridium ions in the insulating phase is crucial for understanding of several exotic phases recently proposed for these materials. We study the spectrum of magnetic excitations in the intermediate-coupling regime for the so-called all-in/all-out magnetic state in pyrochlore iridates with non-magnetic A-site ions (A=Eu,Y), which is found to be preferred in previous theoretical studies. We find that the effect of charge fluctuations on the spin-waves in this regime leads to strong departure from the lowest-order spin-wave calculations based on models obtained in strong-coupling calculations. We discuss the characteristic features of the magnetic excitation spectrum that can lead to conclusive identification of the magnetic order in future resonant inelastic x-ray (or neutron) scattering experiments. Knowledge of the nature of magnetic order and its low-energy features may also provide useful information on the accompanying metal-insulator transition.

8 pages, 5 figures; added references

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• Topological Magnon Bands and Unconventional Superconductivity in Pyrochlore Iridate Thin Films
• X-ray scattering study of pyrochlore iridates: crystal structure, electronic and magnetic excitations
• Interplay of many-body and single-particle interactions in iridates and rhodates
• Topological magnons with nodal-line and triple-point degeneracies: Implications for thermal Hall effect in pyrochlore iridates
• Evolution of Magnetic Excitations Across the Metal-Insulator Transition in a Pyrochlore Iridate Eu${}_2$Ir${}_2$O${}_7$
• Topological and magnetic phases with strong spin-orbit coupling on the hyperhoneycomb lattice
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• Bogoliubov Fermi surfaces from pairing of emergent $j=3/2$ fermions on the pyrochlore lattice
• Intrinsic Magnon Nernst Effects in Pyrochlore Iridate Thin Films
• Longitudinal Spin Seebeck effect in Pyrochlore Iridates with Bulk and Interfacial Dzyaloshinskii-Moriya interaction
• Interplay of uniform U(1) quantum spin liquid and magnetic phases in rare earth pyrochlore magnets : a fermionic parton approach
• Phase Diagram of a Spin-ice Kondo Lattice Model in a Breathing Pyrochlore Lattice
• Electron quasi-itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetism
• Flux fractionalization transition in anisotropic $S=1$ antiferromagnets and dimer-loop models