EFFECTIVE MAGNETIC-ANISOTROPY FIELD OF PD NI MULTILAYERS/

The effective magnetic anisotropy field of Pd/Ni multilayer structures has been investigated. The strain between the substrate and magnetic thin film may contribute significantly to the effective internal field via magnetostriction since Ni is a strong magnetostrictive ferromagne t. The multilayer structures with Ni thicknesses larger than the excha nge length (3.2 nm) were studied by means of FMR at the X-band. Polycr ystalline samples were deposited (rf-sputtered) on Coming glass and mi ca. FMR measurements yield an effective anisotropy field including var ious anisotropy contributions; in our case we have the magnetic shape anisotropy field H-u, the stress-induced anisotropy field H-sigma and the magnetic interaction field H-int. H-sigma was found to be dependen t on the Ni thickness, but was not altered by the thicknesses t(1) and t(2) of Pd for Pd(t(1))/Ni and Pd(t(1))/Ni/Pd(t(2)) structures. The m agnetic interaction field H-int in the Pd(t(1))/Ni/Pd(t(2))/Ni/Pd(t(3) ) structure versus the thickness t(2) of the Pd interlayer (the middle layer) is also altered by stresses. For each value of t(2) (from 1.0 to 5.0 nm) H-int of a more strained film (Coming glass as the substrat e) is smaller than that for a less strained one (mica as the substrate ). The surface mode excitations in the spin wave resonance (SWR) exper iment were used to derive the surface anisotropy energy constant K-s. For the Pd(t(1))/Ni/Pd(t(2))/Ni/Pd(t(3)) structure, K-s is altered by stresses but does not depend on the thickness t(2) of the Pd interlaye r.