Superdirectional beam of surface spin wave

Kotel'nikov Institute of Radio Engineering and Electronics of Russian Academy of Sciences (Fryazino branch) Vvedensky sq.1, 141190, Fryazino, Moscow region, Russia

^(a) amts-f@mail.ru
^(b) svg318@ire216.msk.su
^(c) edwin@ms.ire.rssi.ru

Received: 3 July 2018
Accepted: 23 August 2018

Abstract

The visualized diffraction patterns of a surface spin wave excited by an arbitrarily oriented linear transducer are investigated experimentally in the plane of a tangentially magnetized ferrite film for the case in which the transducer length D is much larger than the wavelength . It is shown experimentally and theoretically that the angular width of a diffracted surface spin wave beam in an anisotropic ferrite film can take values greater or less than and can also be zero. For the last case a superdirectional (non-expanding) beam of the surface spin wave is observed experimentally: the smearing of the beam energy along the film plane is absent and the length of the beam trajectory is maximal . It is found that the well-known Rayleigh criterion used in isotropic media cannot be used to estimate the angular width of spin wave beams. The experimental results are in good agreement with theoretical investigations, predictions, calculations and formulas obtained recently.