Low-temperature spin dynamics of a classical compressible Heisenberg chain

The dynamic spin correlation function of a classical compressible Heisenberg chain is investigated in the low temperature limit. Anharmonic processes, arising from the nonlinearity of the spin equations of motion and from the coupling of the spins to translational degrees of freedom, are taken into account to lowest order. Two-magnon processes and magnon-phonon processes contribute to the spectra. They can give rise to additional resonances but mostly their weight is very small. The main influence of the spin-phonon coupling lies in a change of the width and position of the spin-wave resonance. Comparison is made with previous work.Research assistant of the Belgian National Fund for Scientific Research (N.F.W.O.)