Abstract
Inelastic neutron scattering experiments on the Haldane-gap quantum antiferromagnet are performed at mK temperatures in magnetic fields of almost twice the critical field applied perpendicular to the spin chains. Above a reopening of the spin gap is clearly observed. In the high-field Néel-ordered state the spectrum is dominated by three distinct excitation branches. A theoretical model consistently describing the experimental data is proposed.
- Received 27 June 2003
DOI:https://doi.org/10.1103/PhysRevB.68.134438
©2003 American Physical Society
