M. Sieling et al., MAGNETIC RESONANCES IN ONE-DIMENSIONAL SPIN SYSTEMS NENP AND NINO, Zeitschrift fur Physik. B, Condensed matter, 96(3), 1995, pp. 297-303
We present Electron-Spin-Resonance experiments in the frequency range
35-420 GHz in magnetic fields up to 14 T and with temperatures down to
1.5 K. The quasi-onedimensional S = 1 Spin Systems NENP and NINO exhi
bit similar resonance-modes, which can be associated with transitions
between excited states at q = pi and excitations from the groundstate.
Groundstate-excitation can be explained with regard to a transverse s
taggered field due to inequivalent Ni2+-sites along the chains. Severa
l features are discussed like polarisation-and temperature dependence
of line-intensity and the angular and temperature-dependence of resona
nce-field.