Large Uniaxial Magnetic Anisotropy of Co–Pt Perpendicular Films Induced by Lattice Deformation

Author

Shimatsu, T. ; Okazaki, Y. ; Sato, H. ; Kitakami, O. ; Okamoto, S. ; Aoi, H. ; Muraoka, H. ; Nakamura, Y.

Author_Institution

Res. Inst. of Electr. Commun., Tohoku Univ., Sendai

Volume

43

Issue

6

fYear

2007

fDate

6/1/2007 12:00:00 AM

Firstpage

2995

Lastpage

2997

Abstract

A study of the thickness dependence of the uniaxial magnetic anisotropy K_u of Co-Pt perpendicular films deposited on Ru seed layers was extended over a wide range of Pt content from 10 to 30 at%, to further investigate the origin of the significant increase in K _u on reducing the film thickness, which was previously reported for Co₈₀Pt₂₀/Ru films. K_u increased significantly as the thickness decreased in all series of films with various Pt content. The rate of increase of K_u with reducing thickness became increasingly large as the Pt content decreased. It should be noted that the K_u of 2-nm-thick films was an almost constant 2times10⁷ erg/cm³ over the range of Pt contents studied, although K_u was maximized at 25-30at%Pt content for films thicker than 5 nm. Experimental results suggest that the increase in K_u on reducing the thickness was mostly related to a reduction of the hcp Co-Pt lattice c/a ratio

Keywords

cobalt alloys; magnetic anisotropy; magnetic thin films; platinum alloys; 2 nm; Co-Pt perpendicular films; CoPt; film thickness; hcp Co-Pt lattice c/a ratio; lattice deformation; uniaxial magnetic anisotropy; Anisotropic magnetoresistance; Gold; Lattices; Magnetic anisotropy; Magnetic films; Magnetic materials; Saturation magnetization; Semiconductor films; Shape measurement; Substrates; Co–Pt films; Ru underlayer; fcc volume fraction; hcp lattice; lattice deformation; surface anisotropy; uniaxial magnetic anisotropy;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2007.893126

Filename

4202911