Tuning magnetic properties of FePtCo ternary alloy thin films for magnetic storage device application

FePtCo ternary alloy films have been grown on Si-substrate by co-sputtering of Co with FePt under three conditions i.e., as-deposited, in-situ annealed, and with Cu-underlayer using a DC magnetron sputtering. The film surface roughness, crystal structure, and magnetic properties of these films were investigated. The average surface roughness (Sa and Ra) of these films deposited under three deposition conditions slightly varies in the range of 0.41-2.48 nm with the increase of Co content. The XRD results show that all the films crystallize in a close-packed FCC structure. The lattice parameters and average crystallite size decrease with an increase in Co concentration for all deposited conditions. The magnetic measurement indicates that the as-deposited films exhibit low coercivity and excellent in-plane magnetic anisotropy with a large effective anisotropy energy in the range of 1.22 x 106 1.88 x 107 erg/cc. The increase of Co content in as-deposited FePtCo films leads to a reduction in the saturation magnetization (MS) and Keff by promoting anti-ferromagnetic interaction with FePt sublattice. However, the annealing and insertion of a 2 nm Cu-under-layer further help to enhance the ferromagnetic nature and as a result, the value of MS and Keff is enhanced with an increase of Co content. (c) 2023 Elsevier B.V. All rights reserved.