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This content will become publicly available on June 11, 2019

Title: Spin-orbit coupled systems in the atomic limit: rhenates, osmates, iridates

Motivated by RIXS experiments on a wide range of complex heavy oxides, including rhenates, osmates, and iridates, we discuss the theory of RIXS for site-localized t 2g orbital systems with strong spin-orbit coupling. For such systems, we present exact diagonalization results for the spectrum at different electron fillings, showing that it accesses “single-particle” and “multiparticle” excitations. This leads to a simple picture for the energies and intensities of the RIXS spectra in Mott insulators such as double perovskites which feature highly localized electrons, and yields estimates of the spin-orbit coupling and Hund's coupling in correlated 5d oxides. We present new higher resolution RIXS data at the Re L 3 edge in Ba 2YReO 6 which finds a previously unresolved peak splitting, providing further confirmation of our theoretical predictions. Using ab initio electronic structure calculations on Ba 2MReO 6 (with M=Re, Os, Ir) we show that while the atomic limit yields a reasonable effective Hamiltonian description of the experimental observations, effects such as t 2g–e g interactions and hybridization with oxygen are important. Our ab initio estimate for the strength of the intersite exchange coupling shows that, compared to the d 3 systems, the exchange is one or two orders ofmore » magnitude weaker in the d 2 and d 4 materials, which may partly explain the suppression of long-range magnetic order in the latter compounds. As a way to interpolate between the site-localized picture and our electronic structure band calculations, we discuss the spin-orbital levels of the MO 6 cluster. In conclusion, this suggests a possible role for intracluster excitons in Ba 2YIrO 6 which may lead to a weak breakdown of the atomic J eff = 0 picture and to small magnetic moments.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [3] ; ORCiD logo [5]
  1. Univ. of Toronto, Toronto, ON (Canada). Dept. of Physics; Canadian Institute for Advanced Research, Toronto, ON (Canada)
  2. Univ. of Missouri, Columbia, MO (United States). Dept. of Physics and Astronomy
  3. Univ. of Toronto, Toronto, ON (Canada). Dept. of Physics
  4. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division and Neutron Scattering Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 97; Journal Issue: 23; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; Natural Sciences and Engineering Research Council of Canada (NSERC)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; electronic structure; magnetism; spin-orbit coupling
OSTI Identifier:
1454394
Alternate Identifier(s):
OSTI ID: 1441102; OSTI ID: 1462735