Theory of dipole-exchange spin waves in ultrathin antiferromagnetic films

A spin wave theory is developed for ultrathin antiferromagnetic films in the regime where the effects of the dipole-dipole and exchange interactions may be comparable. A microscopic model with a Hamiltonian representation of the above terms is employed, giving a description of linear spin waves in lowest order and the dominant spin wave interactions as higher-order effects. Applications are made to rutile-structure antiferromagnets (such as MnF2), perovskite-structure antiferromagnets (such as RbMnF3), and layered antiferromagnets (such as K2NiF4), which exhibit quite different behavior. (C) 1999 American Institute of Physics. [S0021-8979(99)39608-0].