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Title: High-energy magnetic excitations in overdoped La 2-xSr xCuO 4 studied by neutron and resonant inelastic X-ray scattering

We have performed neutron inelastic scattering and resonant inelastic x-ray scattering (RIXS) at the Cu-L 3 edge to study high-energy magnetic excitations at energy transfers of more than 100 meV for overdoped La 2₋xSr xCuO 4 with x=0.25 (T c=15 K) and x=0.30 (nonsuperconducting) using identical single-crystal samples for the two techniques. From constant-energy slices of neutron-scattering cross sections, we have identified magnetic excitations up to ~250 meV for x=0.25. Although the width in the momentum direction is large, the peak positions along the (π,π) direction agree with the dispersion relation of the spin wave in the nondoped La 2CuO 4 (LCO), which is consistent with the previous RIXS results of cuprate superconductors. Using RIXS at the Cu-L 3 edge, we have measured the dispersion relations of the so-called paramagnon mode along both (π,π) and (π,0) directions. Although in both directions the neutron and RIXS data connect with each other and the paramagnon along (π,0) agrees well with the LCO spin-wave dispersion, the paramagnon in the (π,π) direction probed by RIXS appears to be less dispersive and the excitation energy is lower than the spin wave of LCO near (π/2,π/2). Thus, our results indicate consistency between neutron inelastic scattering andmore » RIXS, and elucidate the entire magnetic excitation in the (π,π) direction by the complementary use of two probes. The polarization dependence of the RIXS profiles indicates that appreciable charge excitations exist in the same energy range of magnetic excitations, reflecting the itinerant character of the overdoped sample. Lastly, we find a possible anisotropy in the charge excitation intensity might explain the apparent differences in the paramagnon dispersion in the (π,π) direction as detected by the x-ray scattering.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [5] ;  [5] ;  [7] ;  [8]
  1. Japan Atomic Energy Agency (JAEA), Tokai (Japan). Quantum Beam Science Center
  2. Japan Atomic Energy Agency (JAEA), Hyogo (Japan). SPring-8
  3. Tohoku Univ., Sendai (Japan). Inst. for Multidisciplinary Research for Advanced Materials
  4. Tohoku Univ., Sendai (Japan). Inst. for Materials Research
  5. Politecnico di Milano (Italy). CNR-SPIN and Physics Dept.
  6. European Synchrotron Radiation Facility (ESRF), Grenoble (France)
  7. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Instrument and Source Division
  8. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC05-00OR22725; 25390132; 35400333; 24340064
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 91; Journal Issue: 18; Journal ID: ISSN 1098-0121
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States