Thickness dependence of structural and magnetic properties of FePt films

L1₀ ordered FePt films of (001) preferred orientation with different thickness have been prepared by DC magnetron sputtering on CrRu (200) underlayer. The effect of thin film thickness on the structural and magnetic properties was investigated using X-ray diffractometer (XRD) and vibrating sample magnetometer (VSM). Increasing the FePt magnetic layer thickness from 5 to 20nm resulted in improvement of the superlattice FCT-FePt (001) preferred orientation. However, when the FePt thickness is 40nm the FCT-FePt (001) preferred orientation began to deteriorate. The degree of long range ordering increases linearly with the FePt layer thickness. Out-of-plane coercivity shows linear relation with thickness only to 20nm, where a maximum value of 2610Oe is achieved. The initial growth layer and the intrinsic magnetocrystalline anisotropy are calculated. Initial growth layer thickness was found to be within the range of 2.9-3.5nm in our films and the intrinsic magnetocrystalline anisotropy ranges from 1.45×10⁷ to 1.91×10 ⁷erg/cm³, depending on the demagnetisation factor.