Progress of Theoretical Physics
Effect of the Magnetic Field on the des Cloizeaux-Pearson Spin-Wave Spectrum
Norikazu Ishimura, Hiroyuki Shiba
Abstract
The des Cloizeaux and Pearson's exact solution for the spin-wave spectrum of the S=1/2 antiferromagnetic Heisenberg chain is extended to the case of finite external field. It reproduces naturally the des Cloizeaux-Pearson spectrum in the zero-field limit as well as the spin-wave spectrum in the ferromagnetic state for fields larger than the critical field. The results are discuessed by comparing them with predictions of other approximate theories.