We report the results of high-field multi-frequency ESR experiment on the S = 1 Heisenberg antiferromagnetic chain Ni (C5 H14 N2)2 N3(PF6) for the fields up to about 55 T and the frequencies up to about 2 THz. We have found that excitation branches above the critical field (Hc) where the energy gap closes change into one branch around 15 T which becomes close to the paramagnetic line at high fields. The branch above 15 T fits well the conventional antiferromagnetic resonance mode with easy planar anisotropy. We compare the results with those in a weakly coupled antiferromagnetic dimer compound KCuCl3 and discuss the origin of the branches observed above Hc.
- Field induced phase
- High field ESR
- S = 1 antiferromagnetic chain
- Spin excitation
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics