Thickness dependence of structural and magnetic properties of FePt films

Abstract

L1 0 ordered FePt films of (0 0 1) preferred orientation with different thickness have been prepared by DC magnetron sputtering on CrRu (2 0 0) 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 20 nm resulted in improvement of the superlattice FCT-FePt (0 0 1) preferred orientation. However, when the FePt thickness is 40 nm the FCT-FePt (0 0 1) 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 20 nm, where a maximum value of 2610 Oe 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 2.9–3.5 nm in our films and the intrinsic magnetocrystalline anisotropy ranges from 1.45×10 7 to 1.91×10 7 erg/cm 3, depending on the demagnetisation factor.