Interlayer exchange coupling in Co/Cr/Co double-layered recording films studied by spin-wave Brillouin scattering

Exchange coupling between Co layers through a Cr interlayer in sputtered Co/Cr/Co films has been studied by Brillouin scattering of spin waves by changing the thickness of the Cr interlayer up to 50 Å. The Brillouin spectrum consists of two spin-wave modes due to the Co double-layered structure which depends on the Cr-layer thickness. From the frequencies of the spin-wave modes, the interlayer exchange coupling A₁₂ varying with the Cr layer is determined by using Hillebrands´ theory. The exchange coupling through the nonmagnetic layer decreases with increase of the Cr thickness and becomes negligible for the Cr layer thicker than 20 Å. The result is compared with the media noise in double-layered CoCrPt alloy films with a Cr interlayer