Comparative studies of low temperature X-ray diffraction experiments on R2Ir2O7 (R = Nd, Eu, and Pr)

Abstract

The cubic symmetry of pyrochlore iridium oxides R2Ir2O7 (R = Nd, Eu, and Pr) has been investigated by high resolution X-ray diffraction experiments down to 4 K,in order to clarify the relationship between the metal-insulator transition (MIT) and the small structural phase transition suggested by Raman scattering experiments in these compounds. We have found that a small negative thermal expansion of the order of 10^-3 angstroms appears only in Nd2Ir2O7 below the MIT, T_MIT = 34 K, resulting in the magnetovolume effect of the long-range order of Ir moments. However, any breaking of the cubic symmetry of three iridates has not been observed as appearance of superlattice reflections nor splittings of cubic reflections below T_MIT. These results imply that lowering of the cubic symmetry plays a minor role for the change in the electronic state of these compounds, while a formation of the special arrangement of Ir moments plays a major role for the MIT.

6 pages, 4 figures

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Cited by in corpus (24)

• Optical evidence for a Weyl semimetal state in pyrochlore Eu2Ir2O7
• Direct determination of the spin structure of Nd${}_2$Ir${}_2$O${}_7$ by means of neutron diffraction
• X-ray scattering study of pyrochlore iridates: crystal structure, electronic and magnetic excitations
• Electron interactions, spin-orbit coupling, intersite correlations in pyrochlore iridates
• Epitaxial thin films of pyrochlore iridate Bi_{2+x}Ir_{2-y}O_{7-delta}: structure, defects and transport properties
• Dilute stuffing in the pyrochlore iridate $E{u}_{2}I{r}_2{O}_7$
• Non-collinear magnetic structure and multipolar order in Eu${}_2$Ir${}_2$O${}_7$
• Pr${}_2$Ir${}_2$O${}_7$: when Luttinger semimetal meets Melko-Hertog-Gingras spin ice state
• Influence of hydrostatic pressure on the bulk magnetic properties of Eu${}_2$Ir${}_2$O${}_7$
• The interplay between structural, magnetic and electronic states in the pyrochlore iridate Eu2Ir2O7
• A continuous metal-insulator transition driven by spin correlations
• Approaching the quantum critical point in a highly-correlated all-in-all-out antiferromagnet
• Strongly-coupled quantum critical point in an all-in-all-out antiferromagnet
• Evolution of structure and magnetism across the metal-insulator transition in the pyrochlore iridate $($Nd${}_{1-x}$Ca${}_x{)}_2$Ir${}_2$O${}_7$
• Role of spin-phonon and electron-phonon interactions in phonon renormalization of (Eu${}_{1-x}$Bi${}_x$)${}_2$Ir${}_2$O${}_7$ across the metal-insulator phase transition: Temperature-dependent Raman and X-ray studies
• Continuum excitation and pseudospin wave in quantum spin-liquid and quadrupole ordered states of Tb${}_{2+x}$Ti${}_{2-x}$O${}_{7+y}$
• Magnetotransport of single crystal Sm${}_2$Ir${}_2$O${}_7$ across the pressure-induced quantum-critical phase boundary
• Unified description of resistivity and thermopower of Pr${}_2$Ir${}_2$O${}_7$: possible influence of crystal field excitation in a Kondo lattice
• Non-Fermi liquid regime in metallic pyrochlore iridates: Quantum Griffiths singularities
• Mapping the structural, magnetic and electronic behavior of (Eu${}_{1-x}$Ca${}_x$)${}_2$Ir${}_2$O${}_7$ across a metal-insulator transition
• Electron quasi-itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetism
• Optical conductivity of the metallic pyrochlore iridate Pr${}_2$Ir${}_2$O${}_7$: Influence of spin-orbit coupling and electronic correlations on the electronic structure
• Impurities in 3D quadratic band-touching Luttinger semimetals : Friedel and RKKY oscillations
• Visualization of spin-orbit entangled 4f electrons in crystalline materials