Engineering the Exchange Spin Waves in Graded Thin Ferromagnetic Films.

The results of experimental and theoretical studies of standing spin waves in a series of epitaxial films of the ferromagnetic Pd 1- x Fe x alloy (0.02 < x < 0.11) with different distributions of the magnetic properties across the thickness are presented. Films with linear and stepwise, as well as more complex Lorentzian, sine and cosine profiles of iron concentration in the alloy, and thicknesses from 20 to 400 nm are considered. A crucial influence of the magnetic properties profile on the spectrum of spin wave resonances is demonstrated. A capability of engineering the standing spin waves in graded ferromagnetic films for applications in magnonics is discussed.