The transport of magnetization and of spin-spin energy are calculated numerically for classical gyromagnets, coupled by truncated dipole-dipole and nearest-neighbor exchange interactions, on sc, bcc, and fcc cubic lattices. For the exchange case the results agree with previous theory, and also agree with experiments on ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ for diffusion of magnetization (but not of spin-spin energy). For the case of dipole-dipole coupling, the results are in satisfactory agreement with previous theory for the angular average of the Zeeman diffusion, but disagree with experiment. Calculations are also presented for a lattice containing alternating moments of two different species: These show how the attenuation of diffusion by foreign spins (‘‘diffusion barrier’’) depends independently on the moment and gyromagnetic ratio of the foreign species.

• Received 8 April 1991

DOI:https://doi.org/10.1103/PhysRevB.45.748