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Title: Strong anisotropy within a Heisenberg model in the J eff = 1 2 insulating state of Sr 2 Ir 0.8 Ru 0.2 O 4

The dispersive magnetic excitations in Sr 2IrO 4 have previously been well described within an isospin-1/2 Heisenberg model on a square lattice that revealed parallels with La 2CuO 4. In this paper, we investigate the inelastic spectra of Sr 2Ir 0.8Ru 0.2O 4 with resonant inelastic x-ray scattering (RIXS) at the Ir L 3 edge. The results are well described using linear spin-wave theory within a similar Heisenberg model applicable to Sr 2IrO 4; however, the disorder induced by the substitution of 20% Ir 4+ ions for Ru 4+ removes longer range exchange interactions. A large spin gap (40 meV) is measured indicating strong anisotropy from spin-orbit coupling that is manifest due to the altered magnetic structure in Sr 2Ir 0.8Ru 0.2O 4 with c-axis aligned moments compared to the basal plane moments in the parent. Finally, collectively the results indicate the robustness of a Heisenberg model description even when the magnetic structure is altered and the J eff = 1/2 moments are diluted.
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division
  2. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source
  3. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 22; 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)
Contributing Orgs:
Univ. of Tennessee, Knoxville, TN (United States)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1339404
Alternate Identifier(s):
OSTI ID: 1338085