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Title: Magnetic ground state of Sr 2 IrO 4 and implications for second-harmonic generation

The currently accepted magnetic ground state of Sr 2IrO 4 (the -++- state) preserves inversion symmetry. This is at odds, though, with recent experiments that indicate a magnetoelectric ground state, leading to the speculation that orbital currents or more exotic magnetic multipoles might exist in this material. In this paper, we analyze various magnetic configurations and demonstrate that two of them, the magnetoelectric -+-+ state and the nonmagnetoelectric ++++ state, can explain these recent second-harmonic generation (SHG) experiments, obviating the need to invoke orbital currents. The SHG-probed magnetic order parameter has the symmetry of a parity-breaking multipole in the -+-+ state and of a parity-preserving multipole in the ++++ state. We speculate that either might have been created by the laser pump used in the experiments. An alternative is that the observed magnetic SHG signal is a surface effect. Finally, we suggest experiments that could be performed to test these various possibilities and also address the important issue of the suppression of the RXS intensity at the L 2 edge.
 [1] ;  [2]
  1. Univ. of Rennes 1 (France). Inst. of Physics of Rennes. Dept. of Materials and Nanoscience
  2. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 7; Journal ID: ISSN 2469-9950
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)
Contributing Orgs:
Univ. of Rennes 1 (France)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; magnetism; ab initio calculations; resonant inelastic x-ray scattering; x-ray absorption spectroscopy
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1305442