Ferromagnetic resonance in CoZr/Ag/CoZr trilayer films

A series of CoZr(200 /spl Aring/)/Ag(t/sub Ag/)/CoZr(200 /spl Aring/) trilayers with Ag interlayer thickness t/sub Ag/ in the range of 10-160 /spl Aring/ was deposited on Si[100] wafers at room temperature by using a magnetron sputtering system. In order to understand the dependence of the magnetic exchange interaction between ferromagnetic Co/sub 84/Zr/sub 16/(at.%) layers separated by nonmagnetic Ag layers on the t/sub Ag/, we investigated the FMR spectra. The coupling strength increases with increasing t/sub Ag/ up to 20 /spl Aring/ with a maximum value of 2.0 kOe, but decreases rapidly with increasing t/sub Ag/ in the range of 40-100 /spl Aring/. Finally, the value approaches zero above 120 /spl Aring/. The coupling strength is positive for all samples.