Correlation among magnetic properties, perpendicular magnetic recording properties and microstructure of [Co85Cr15/Pt]20 multilayers

The [Co85Cr15/Pt](20) multilayers with Pt underlayers were prepared by magnetron sputtering and the effects of sputtering gas pressure on microstructure and magnetic properties Of [Co85Cr15/Pt](20) multilayers were studied. The results show that sputtering Ar gas pressure has a great effect on the microstructure, perpendicular magnetic anisotropy and the coercivity of [Co85Cr15/Pt](20) multilayers. For all samples, we have the effective magnetic anisotropy constant K-eff > 0, and all samples showed perpendicular magnetic anisotropy. With increasing sputtering Ar gas pressure, the perpendicular and in-plane coercivity of the samples increase, but the effective magnetic anisotropy constant decreases. The coercivity of Pt(20 nm)/[( Co85Cr15 (0.5 nm)/Pt(1.5 nm)](20) multilayers sputter-depositied at 1.6 Pa Ar gas pressures is increased to 130 kA/m. The Pt(20 nm)/ [(Co85Cr15(0.5 nm)/Pt(1.5 nm)](20) multilayers display perpendicular magnetic anisotropy and can be used as perpendicular magnetic recording media. The images of atomic force microscopy show that both average grain size and the surface roughness increase with increasing sputtering Ar pressure, which leads to the enhancement of perpendicular coercivity and the decrease of effective magnetic anisotropy constant.