title: Anomalous high-energy spin excitations in the high-Tc superconductor-parent antiferromagnet La₂CuO₄.
abstract: Inelastic neutron scattering is used to investigate the collective magnetic excitations of the high-temperature superconductor-parent antiferromagnet La2CuO4. We find that while the lower energy excitations are well described by spin-wave theory, including one- and two-magnon scattering processes, the high-energy spin waves are strongly damped near the (1/2, 0) position in reciprocal space and merge into a momentum dependent continuum. This anomalous damping indicates the decay of spin waves into other excitations, possibly unbound spinon pairs.
authors.affiliation: H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK.
authors.forename: N S
authors.initials: NS
authors.lastname: Headings
authors.forename: S M
authors.initials: SM
authors.lastname: Hayden
authors.forename: R
authors.initials: R
authors.lastname: Coldea
authors.forename: T G
authors.initials: TG
authors.lastname: Perring