CRITICAL SCATTERING OF ELECTROMAGNETIC-WAVES ON SPIN FLUCTUATIONS IN NONSATURATED MAGNETIC-FILMS UNDER ACOUSTIC PUMP

The theoretical and experimental investigation of the microwave (MW) c ombination scattering on spin fluctuations (SF) in the yttrium iron ga rnet film under acoustic pump were pursued. MW frequency f congruent t o 3.5-4.1 GHz was well above spin wave spectrum at a preassigned magne tic field. At the external magnetic field range H-0 congruent to 5-40 Oe one (or more) intensity peaks of MW scattering were observed. The p ositions of these peaks do not depend on MW and surface acoustic wave (SAW) amplitudes and frequencies and depend heavily on the magnetic fi eld directions in a film plane. Because these phenomena were closely a ssociated with the domain walls (DW) reorientation or at the domain st ructure transformations, e.g., at the flexural instability of DW, one may speculate that critical scattering of MW on SAW and SF was observe d. Cross section for such scattering was calculated. In nonsaturated m agnetic films the phenomena of MW scattering on SAW and spin fluctuati ons at high amplitudes of the MW and SAW were investigated as well. In the area of external magnetic fields H-0 greater than or equal to 250 Oe a stepped dependence of intensity of scattering MW was observed. T here is no appropriate explanation of this effect now.