SPIN-DYNAMICS STUDY OF THE CLASSICAL FERROMAGNETIC XY CHAIN IN A RANDOM FIELD

The classical one-dimensional XY model in a symmetry-breaking Gaussian-distributed random magnetic field was studied using an ultrafast, vectorized spin-dynamics program on a Cray Y-MP. We calculated the time and space-displaced spin-spin correlation functions, which was then Fourier-transformed to get the neutron-scattering law S(q,omega). We see a clear change of the different contributions when the random field is switched on. At low temperatures the random field induces significant increases in the soliton density.