ENERGY OF SPIN-WAVE EXCITATIONS IN NICKEL MONOLAYERS

The spin wave stiffness constant D ((q) over cap) of unsupported Fee ( 100), (110), and (111) nickel monolayers are calculated for different directions, (q) over cap, of spin wave propagation. It is shown that D is isotropic for the (100) and (111) orientations, and highly anisotr opic for the (110) orientation. Results indicate that the strength of the exchange coupling between nearest neighbour magnetic moments is qu ite sensitive to the effective space dimensionality as well as the cry stalline structure of the system.