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

We have investigated the structural, electronic, and magnetic properties of the pyrochlore iridates Eu 2Ir 2O 7 and Pr 2Ir 2O 7 using a combination of resonant elastic x-ray scattering, x-ray powder diffraction, and resonant inelastic x-ray scattering (RIXS). The structural parameters of Eu 2Ir 2O 7 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 Eu 2Ir 2O 7 and Pr 2Ir 2O 7 using high-resolution Ir L- 3-edge RIXS. In spite of very different ground state properties, we find that 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 single-crystal samples of "Eu-rich" Eu 2Ir 2O 7 (found to possess an actual stoichiometry of Eu 2.18Ir 1.82O 7.06) we observe highly damped magnetic excitations at ~45 meV, which display significant momentummore » dependence. Here, we compare these results with recent dynamical structure factor calculations« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [3] ;  [3] ;  [4] ;  [1] ;  [1] ;  [1]
  1. Univ. of Toronto, Toronto, ON (Canada)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Seoul National Univ., Seoul (Korea, Republic of)
  4. Univ. of Ottawa, Ottawa, ON (Canada)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 2; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Canada Foundation for Innovation (CFI)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1339452