Quasioptics of Magnetostatic Waves

Abstract

As a result of a large deceleration, magnetostatic waves are characterized by a relatively small wavelength in comparison with the wavelength of electromagnetic waves of the same frequency in vacuum. In typical cases in thin YIG layers the wavelength of magnetostatic waves (MSW) is from one to a hundred micrometres, i.e. much smaller than the linear size of waveguides of magnetostatic structures: 103 – 104 times smaller. This condition is even more appropriate if we do not use magnetostatic waveguides, but instead thin YIG films on the substrate with diameters of 50 – 100 mm and more, produced in series. In such structures magnetostatic waves can exist in the form of magnetostatic beams which are similar to light beams propagating in a transparent medium. Such a beam propagates “slowly” in a structure (ten thousand times more slowly than a light beam) — either on the surface of a thin film (surface wave) or in the volume of a film (volume wave). A strict mathematical definition of this beam does not exist. We can only say that in optics a beam is a finite rather narrow bundle of electromagnetic waves which can exist independently of other beams [18].