Spin resonance of the triplet excitations is studied experimentally in the Haldane magnet Pb Ni2 V2 O8. The absorption spectrum has features of spin S=1 resonance in a crystal field, with all three components, ±1 0 and -1 1, being observable. The resonance field is temperature dependent, indicating the renormalization of excitation spectrum in the interaction between the triplets. Magnetic resonance frequencies and critical fields of the magnetization are consistent with a boson version of the macroscopic field theory while they contradict the fermion version and the previously used approach of noninteracting spin chains.
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2008 Mar 6