AFM, XRD and HRTEM Studies οf Annealed FePd Thin Films

Abstract

Ferromagnetic FePd L10 ordered alloys are highly expected as forthcoming high-density recording materials, because they reveal a large perpendicular magnetocrystalline anisotropy [1]. The value of the magnetic anisotropy of FePd alloy strongly depends on the alloy composition, degree of alloy order as well as on the crystallographic grain orientation. In particular, to obtain the perpendicular anisotropy, it is necessary to get the films with (001) texture. One of the successful methods, which allows one to obtain highly ordered alloy, is a subsequent deposition of Fe and Pd layers, followed by an annealing at high temperature. This paper presents the study of the FePd thin alloy film structure changing in the result of high temperature annealing. During the annealing in high vacuum, the measurements of electrical resistance were performed, indicating the regions of different structure evolution. Changes in the crystal structure and surface morphology induced by thermal treatment were investigated by X-ray diffraction, atomic force microscopy, as well as high resolution transmission electron microscopy and then compared with electrical resistivity measurement. The slow thermal annealing of the deposited layers leads to the formation of L1 0 ordered FePd alloy with preferred (111) grain orientation. After the annealing at the highest used temperature, the dewetting process was observed, resulting in a creation of well oriented, regular nanoparticles.

Cross-sectional characterization of the dewetting of a Au/Ni bilayer film

“…The experimental observations suggest that Au diffusion outruns relaxation of the Ni film and, therefore, forms a predominant Au/SiO 2 interface. Surprisingly, no remaining Au absorption layers on top of 14 agglomerated Ni grains were detected by either EDXS elemental mapping or atomic resolution HAADF-STEM imaging.…”

“…Once a hole in the film has formed, it will grow subsequently by continuous diffusion exposing the free surface of the underlying substrates [9]. Wetting-dewetting transitions have been extensively studied in single component films, but only few studies are reported for multi-component films [10][11][12][13][14][15][16][17][18].…”

“…Single crystal 3 Au/Fe and Fe/Pd bilayer films showed enhanced thermal stability upon annealing due to alloying effects [13,14].…”

Determination of grain shape of laser-irradiated FePdCu thin alloy films

“…It is worth mentioning, that the model does not take into account the temperature dependencies of the material properties such as absorption, density, specific heat and thermal conductivity, and assumes, that between laser pulses they do not change. The peak temperature of 500 circ C was chosen basing on results of our previous investigations, [9,11,12] which showed that it is the minimum temperature required to induce a diffusion process, and to start transformation from multilayer system into ordered alloy.…”

“…• C. Usually such annealing temperature is sufficient [9,10] to fabricate the chemically ordered L1 0 alloy, but is not large enough to produce the alloy with a (001) texture, which is needed to obtain perpendicular magnetic anisotropy. To reduce the temperature of L1 0 structure formation and to induce (001) texture the FePd alloy was doped with Cu, as it was observed in our previous studies.…”