Strong impact of all-in all-out magnetic order on magnetic and lattice dynamics in pyrochlore iridates studied by Raman spectroscopy

ORAL

Abstract

We perform Raman spectroscopy on pyrochlore Eu2Ir2O7 which undergoes a paramagnetic-to-antiferromagnetic transition, as well as paramagnetic counterpart Pr2Ir2O7.
The first polarization analysis combined with density functional theory allows us to assign all observed peaks to six optical phonons without any ambiguity.
An additional peak clearly shows up below the transition temperature TN at 210 cm-1 which is reasonably close to the single-magnon excitation energy estimated from the resonant inelastic x-ray scattering.
Simultaneously, the Eg phonon, involving Ir-O-Ir bond bending motion, exhibits a remarkable softening by 35 cm-1 that is by one order of magnitude larger than those in 3d magnets.
These findings imply that the magnon-phonon coupling is unconventionally strong in this system, and intriguingly, the combination of the antiferromagnetic super-exchange and Dzyaloshinskii-Moriya interaction can play a vital role in the all-in all-out magnetic order, providing an important insight into the exotic phase transition in $5d$ transition metal oxides.

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Presenters

  • Kentaro Ueda

    Department of Applied Physics and Quantum-Phase Electronics Center, University of Tokyo, University of Tokyo

Authors

  • Kentaro Ueda

    Department of Applied Physics and Quantum-Phase Electronics Center, University of Tokyo, University of Tokyo

  • Ryoma Kaneko

    Department of Applied Physics and Quantum-Phase Electronics Center, University of Tokyo, University of Tokyo

  • Alaska Subedi

    Universite Paris-Saclay, Centre de Physique Theorique, Ecole Polytechnique

  • Matteo Minola

    Max-Planck-Institut, Max Planck Institute Stuttgart

  • Bumjoon Kim

    Pohang University, Pohang University of Science and Technology, Physics, Pohang University of Science and Technology, Department of Physics, POSTECH, Institute for Basic Science, Department of Physics, Pohang University of Science and Technology

  • Jun Fujioka

    Graduate School of Pure and Applied Sciences, University of Tsukuba, University of Tsukuba, University of Tokyo and JST-PRESTO

  • Yoshinori Tokura

    RIKEN Center for Emergent Matter Science (CEMS), RIKEN Center for Emergent Matter Science, RIKEN CEMS, RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan, Center for Emergent Matter Science (CEMS), RIKEN, Department of Applied Physics and Quantum-Phase Electronics Center, University of Tokyo, University of Tokyo, University of Tokyo and RIKEN CEMS, CEMS, RIKEN, Center for Emergent Matter Science, RIKEN, Department of Applied Physics, University of Tokyo, University of Tokyo and RIKEN-CEMS

  • Bernhard Keimer

    max planck inst., Max Planck Institute for Solid State Research, max planck institut, Max-Planck-Institut, Max Planck Institute for Solid State Research, Stuttgart, Germany, Max Planck Institute Stuttgart