Solitons in magnetic chains: A functional integration approach

The free energies and the static spin correlation functions for the 2π- and π-sine-Gordon systems are calculated from a functional integration approach. The free energies for these systems are rather similar but the soliton contributions to the static two-spin correlation functions can be drastically different. The reasons for these behaviors are discussed, and the nature of the T = 0 phase transitions for the π system is briefly analyzed.