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arXiv · 1510.07934

X-ray scattering study of pyrochlore iridates: crystal structure, electronic and magnetic excitations

J. P. Clancy·H. Gretarsson·E. K. H. Lee·Di Tian·J. Kim·M. H. Upton·D. Casa·T. Gog·Z. Islam·Byung-Gu Jeon·Kee Hoon Kim·S. Desgreniers·Yong Baek Kim·S. J. Julian·Young-June Kim
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Abstract

We have investigated the structural, electronic, and magnetic properties of the pyrochlore iridates Eu2Ir2O7 and Pr2Ir2O7 using a combination of resonant elastic x-ray scattering, x-ray powder diffraction, and resonant inelastic x-ray scattering (RIXS). The structural parameters of Eu2Ir2O7 have been examined as a function of temperature and applied pressure, with a particular emphasis on regions of the phase diagram where electronic and magnetic phase transitions have been reported. We find no evidence of crystal symmetry change over the range of temperatures (~6 to 300 K) and pressures (~0.1 to 17 GPa) studied. We have also investigated the electronic and magnetic excitations in single crystal samples of Eu2Ir2O7 and Pr2Ir2O7 using high resolution Ir L3-edge RIXS. In spite of very different ground state properties, we find these materials exhibit qualitatively similar excitation spectra, with crystal field excitations at ~3-5 eV, spin-orbit excitations at ~0.5-1 eV, and broad low-lying excitations below ~0.15 eV. In Eu2Ir2O7 we observe highly damped magnetic excitations at ~45 meV, which display significant momentum dependence. We compare these results with recent dynamical structure factor calculations.

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J. P. Clancy, H. Gretarsson, E. K. H. Lee, Di Tian, J. Kim, M. H. Upton, D. Casa, T. Gog, Z. Islam, Byung-Gu Jeon, Kee Hoon Kim, S. Desgreniers, Yong Baek Kim, S. J. Julian, Young-June Kim. 2015-10-27. X-ray scattering study of pyrochlore iridates: crystal structure, electronic and magnetic excitations. https://doi.org/10.1103/physrevb.94.024408

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