Effects of sputtering pressure on magnetic and magneto-optical properties in compositionally modulated Co/Pd thin films

We have investigated the effects of sputtering Ar gas pressure on magnetic and magneto-optical properties in compositionally modulated Co/Pd thin films. The samples were prepared by dc magnetron sputtering from 2-in.-diam Co and Pd targets by alternately exposing the substrates to targets. Sputtering Ar gas pressure was varied from 2 to 30 mTorr. All samples had same bilayer thicknesses composed of 2-Å-thick Co and 9-Å-thick Pd sublayers. It was observed that the intrinsic uniaxial anisotropy energy, magnetization, and polar Kerr rotation were monotonically decreased with increasing Ar gas pressures more than about 10 mTorr. Interestingly enough, the coercivity showed a thirtyfold enhancement as Ar gas pressure varied from 2 to 30 mTorr. We believe that the results are mainly ascribed to the variation of microstructure with sputtering Ar gas pressure.