Spin polarization and magnetic properties in Co[sbnd]Nb/Pd and Co[sbnd]Nb/Pd/Si/Pd multilayers

Abstract

The CoNb/Pd/Si/Pd and CoNb/Pd multilayers were prepared by RF sputtering method and the spin polarization of Pd layers was systematically studied by magnetic measurements. Not only the increment but also the reduction of saturation magnetization of the multilayers was found as compared with the saturation magnetization of the bulk CoNb alloy. The magnetism and the spin polarization of Pd layers were strongly influenced by the effect of low-dimensional magnetism and the interlayer coupling. For CoNb/Pd(tPd)/Si/Pd(tPd) multilayers, the saturation magnetization increases when the thickness of Pd layers tPd increases from 5 to 25 Å, and approaches a constant when tPd further increases. For CoNb/Pd(tPd) multilayers, the saturation magnetization periodically oscillates when tPd increases. The oscillatory period is about 10 Å. The oscillatory magnetization is caused by the oscillatory polarization of Pd layers. For CoNb(tCo)/Pd(15 Å) multilayers, the saturation magnetization also shows an oscillatory behaviour when the thickness of CoNb layers tCo increases. The magnetic anisotropy also oscillates periodically as tPd increases, which can be attributed to the oscillatory polarization of Pd layers.