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Polarized-Neutron Observation of Longitudinal Haldane-Gap Excitations in Nd{sub 2}BaNiO{sub 5}

Journal Article · · Physical Review Letters
 [1]; ;  [2];  [3];  [4];  [5]
  1. DRFMC/SPSMS/MDN, CENG, 17 rue des Martyrs, 38054 Grenoble Cedex (France)
  2. Department of Physics, Aoyama-Gakuin University, 6-16-1, Chitosedai, Setagaya-ku, Tokyo 157 (Japan)
  3. Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)
  4. Oak Ridge National Laboratory, Building 7692, MS 6393, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States)
  5. Institut Laue-Langevin, Avenue des Martyrs, Grenoble Cedex 9 (France)
Polarized and unpolarized inelastic neutron scattering is used to study Haldane-gap excitations in the mixed-spin linear-chain antiferromagnet Nd{sub 2}BaNiO {sub 5} . The longitudinal mode, polarized along the direction of ordered moments, is observed for the first time. The model of isolated Haldane chains in a static staggered exchange field, that is known to work very well for static properties and transverse spin excitations in R{sub 2}BaNiO{sub 5} compounds, fails to explain new results for the longitudinal spin gap. {copyright} {ital 1999} {ital The American Physical Society}
Research Organization:
Brookhaven National Laboratory
DOE Contract Number:
AC02-98CH10886; AC05-96OR22464
OSTI ID:
329721
Journal Information:
Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 11 Vol. 82; ISSN 0031-9007; ISSN PRLTAO
Country of Publication:
United States
Language:
English