Gd/Fe multilayers with an anisotropy changing from in-plane to perpendicular for MSR applications

One of the most important properties for the magnetically induced super resolution (MSR) with in-plane magneto-optical (MO) media is a magnetisation switching from in-plane to perpendicular direction at an elevated temperature. Experimental studies of this switching in sputtered Gd/Fe multilayered films as a function of the periodicity λ, the Ar gas pressure and the Gd content are presented in this paper. For low Ar gas pressures and with a Gd atomic percentage of 27%±2.5% the magnetic anisotropy was found to depend strongly on the periodicity. At room temperature the magnetisation direction is perpendicular to the film plane for small λ (11 Å) and becomes in-plane for increasing λ. Higher gas pressures lead to a stronger in-plane anisotropy. The magnetisation switching from in-plane to perpendicular at elevated temperatures required for MSR has been observed in all films having a periodicity between 13 Å and 20 Å for low gas pressures and between 11 Å and 12 Å for intermediate gas pressures. This switching could not be observed for high sputtering pressures