Title :
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
fDate :
6/1/2007 12:00:00 AM
Abstract :
A study of the thickness dependence of the uniaxial magnetic anisotropy Ku 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. Ku increased significantly as the thickness decreased in all series of films with various Pt content. The rate of increase of Ku with reducing thickness became increasingly large as the Pt content decreased. It should be noted that the Ku of 2-nm-thick films was an almost constant 2times107 erg/cm3 over the range of Pt contents studied, although Ku was maximized at 25-30at%Pt content for films thicker than 5 nm. Experimental results suggest that the increase in Ku 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;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2007.893126
