@article{b38e7da4cba74fdaa49265e2623d7789,
title = "The origin of (001) texture evolution in FePt thin films on amorphous substrates",
abstract = "A theoretical study has been performed to rationalize the strong evolution of (001) texture during postannealing of deposited Fe50Pt 50 thin films on amorphous substrates, by comparing calculated strain energies of several crystals with different orientations under presumed strain conditions. An atomistic calculation method based on an empirical interatomic potential (MEAM) was used to calculate strain and surface energies and atomic force microscope experiments were carried out to confirm the surface energy calculation. The (001) texture evolution could not be explained using traditional factors, the surface energy anisotropy and the in-plane strain. It was found that the strain from the L10 ordering transformation that occurs during postannealing can make the (001) crystal (crystal with [001] crystallographic orientation into the surface normal) energetically most stable among those with various orientations. It is proposed that the occurrence of anisotropic strain due to ordering transformations should be considered as a key factor that affects the texture evolution and that enhanced ordering and recrystallization kinetics is necessary to maximize the strain effect.",
author = "Kim, {Jae Song} and Koo, {Yang Mo} and Lee, {Byeong Joo} and Lee, {Seong Rae}",
note = "Funding Information: This work has been financially supported by the Nanocomposites & E-Beam Technology Center, a National Research Laboratory sponsored by the Ministry of Science and Technology of Korea, and a National R&D Project for Nano Science and Technology (Grant No. M1-0213-04-0002). Table I. Calculated surface energy of ordered L 1 0 FePt crystal. Surface energy ( erg ∕ cm 2 ) a (1 1 1) 2198 (1 0 1) 2714 (1 1 0) 2650 (1 0 0) 2719 (0 0 1) 2740 a Reference 25 . Table II. Calculated elastic constants of ordered L 1 0 and disordered fcc Fe 50 Pt 50 crystals ( 10 12 dyn ∕ cm 2 or 100 GPa ). FePt ( L 1 0 ) a FePt (fcc) a C11 3.042 2.912 C33 2.420 — C12 2.226 2.053 C13 1.973 — C44 1.065 0.951 C66 0.408 — a Reference 25 . FIG. 1. Illustration of the procedure for the calculation of joint effect of (a) transformation strain and (b) in-plane strain. FIG. 2. Assumptions made for the relaxation of crystals into the surface normal direction during the biaxial in-plane strain. (a) Poisson{\textquoteright}s ratio of 0.33 (b) a plane-stress condition FIG. 3. XRD patterns of FePt alloy films on various Sr Ti O 3 substrates, (111), (011), and (001). The thickness of as-deposited films is 20 nm . All films were postannealed at 550 ° C for 900 s with RTA. FIG. 4. Surface morphologies of FePt thin films on (a) (111), (b) (001), and (c) (011) Sr Ti O 3 substrates. FIG. 5. The shape of cubic crystals covered with (111) and (001) surface planes (a) with no external limitation for growth and (b) with a limited growth into a [111] direction. FIG. 6. Calculated strain energy of L 1 0 ordered FePt crystals with various orientations as a function of biaxial in-plane strains under relaxations into the surface normal direction according to (a) the Poisson{\textquoteright}s ratio and (b) a plane-stress condition. Each index indicates the crystallographic orientation normal to the film surface. FIG. 7. Calculated strain energy of L 1 0 ordered FePt crystals with order/disorder transformation strain and biaxial in-plane strains under relaxations into the surface normal direction according to (a) the Poisson{\textquoteright}s ratio and (b) a plane-stress condition. ",
year = "2006",
month = mar,
day = "1",
doi = "10.1063/1.2176088",
language = "English",
volume = "99",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics Publising LLC",
number = "5",
}