Dispersion relation of nutation surface spin waves in ferromagnets

Inertia effects in magnetization dynamics are theoretically shown to result a different type of spin waves, i.e. nutation surface which propagate at terahertz frequencies in-plane magnetized ferromagnetic thin films. Considering the magnetostatic limit, neglecting exchange coupling, we calculate dispersion relation and group velocity, find be slower than velocity conventional (precession) waves. In addition, that waves backward Furthermore, show inertia causes decrease frequency precession namely volume The magnitude depends on magnetic properties film its geometry.