Effect of sputtering pressure of Pd underlayer on the perpendicular magnetic anisotropy in Co/Pd multilayered thin films

The magnetic properties of Co/Pd multilayers, in particular the perpendicular magnetic anisotropy, have been analyzed as a function of the sputtering pressure of Pd underlayer. With an increase of sputtering pressure of the underlayer from 6 mTorr to 25 mTorr, perpendicular coercivity of the multilayers increased with a slight decrease of saturation magnetization, and the increment of the coercivity was larger for the films with thinner cobalt layers. From the anisotropy analysis, it was found that the interface anisotropy energy decreased from 0.390 erg/cm² to 0.255 erg/cm² because of the interface roughening of the multilayers, which was mainly responsible for the decrease of perpendicular anisotropy, while the volume anisotropy energy increased from -11.37×10⁶ erg/cm³ to -7.90×10⁶ erg/cm³. The abnormally large intrinsic volume anisotropy energies of the multilayers with thin cobalt layers (<7 Å) appears to suggest the noticeable contribution of magnetoelastic effect to the perpendicular anisotropy of the films