Two-magnon states of the alternating ferromagnetic Heisenberg chain

Abstract
The authors examine the nature of two-magnon excitations in the alternating bond ferromagnetic S=1/2 spin chain. Both a direct analytic approach as well as a method based on a scaling transformation are used to study the bound state branches and their relationship to the two-magnon continuum. Several features are expected to be observable in two-magnon Raman scattering experiments.