Title :
Crystal Structure as an Origin of High-Anisotropy Field of FeCoB Films With Ru Underlayer
Author :
Hashimoto, A. ; Hirata, K. ; Matsuu, T. ; Saito, S. ; Nakagawa, S.
Author_Institution :
Dept. of Phys. Electron., Tokyo Inst. of Technol., Tokyo
Abstract :
The origin of high uniaxial magnetic asnisotropy in FeCoB thin films was investigated by focusing on the changes in FeCo crystal distortion and alignment. The films were prepared by facing targets sputtering using F88.8Co27.2B4 alloy targets and examined with X-ray diffraction (XRD) analysis. Preparation of a Ru underlayer showed reduction of coercivity Hc from 130 to 14 Oe and developed remarkably high-anisotropy field Hk, of 500 Oe. FeCo(110) of the FeCoB film with a Ru underlayer revealed an oblique crystal growth and a preferred orientation in the film plane that possessed (110) [110] along the easy axis. FeCo(110) lattice spacing has 0.5% expansion along the easy axis, which induces that the magnetoelastic energy -Eelastic of 3.8 times 105 erg/cm3 exists along the easy axis due to an inverse magnetostriction effect. The estimated Hk from the Eelastic was 470 Oe, which corresponded well with the measured Hk of 500 Oe. This indicates that the strain in FeCo lattice is the origin of the remarkably high magnetic anisotropy.
Keywords :
X-ray diffraction; boron alloys; cobalt alloys; coercive force; crystal structure; ferromagnetic materials; iron alloys; magnetic thin films; magnetoelastic effects; magnetostriction; metallic thin films; texture; F88.8Co27.2B4; FeCo(110); FeCo(110) lattice spacing; X-ray diffraction; XRD; coercivity; crystal alignment; crystal distortion; crystal structure; high-anisotropy field; inverse magnetostriction effect; magnetoelastic energy; preferred orientation; thin films; uniaxial magnetic asnisotropy; Crystalline texture; FeCoB; Ru; high-anisotropy field; stress-induced magnetic anisotropy;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2008.2002252
