The Influence of Dissipation on the Dispersion Characteristics of Surface Spin Waves

Resumo

Dissipation of surface spin waves propagating in arbitrary directions in a magnetized ferromagnetic film is studied. It is shown that the allowance for dissipation restricts the domain of possible wave vectors to a finite region and leads to the appearance above this region of the continuation of a dispersion surface in the form of an inverted cap with a negative slope and a large damping of the waves. It is noted that the solution gives an infinite number of almost coincident dispersion surfaces with a sharp increase in the damping coefficient with each next surface, so that the waves become practically nonpropagating. The analysis of the dispersion surfaces shows that the lower part has a positive slope and describes forward waves, the damping of which is proportional to a small dissipation constant but, in the upper part of the surface, the damping coefficient sharply increases. It is found that the directions of the group velocities of the waves substantially change in comparison with a dissipationless medium and some frequency and angular restrictions on the propagation of surface waves also become different.