Title :
Suppression of Switching-Field Variation by Surface Oxidation Depending on the Shape of the CoFeB Free Layer
Author :
Takenaga, T. ; Kuroiwa, T. ; Tsuchimoto, J. ; Matsuda, R. ; Ueno, S. ; Takada, H. ; Abe, Y. ; Tokuda, Y.
Author_Institution :
Adv. Technol. R&D Center, Mitsubishi Electr. Corp., Amgasaki
fDate :
6/1/2007 12:00:00 AM
Abstract :
We investigated the suppression of the variation of switching field Hsw by reducing magnetization M in submicron-sized magnetic tunnel junctions (MTJs) by oxidizing the surface of the CoFeB layer. Examination confirmed a reduction in the M of oxidized CoFeB film. The results also confirmed that oxidization enlarges anisotropy field Hk of CoFeB films. We applied this film to the free layer of submicron-sized MTJs of various aspect ratios. The results revealed that Hsw variation depending on the aspect ratio is reduced more with oxidation than without. We confirmed that Hsw variation in submicron-sized MTJs originating in the CoFeB free layer´s shape decreased due to the oxidation, which reduced the switching field distribution (SFD) for the MTJs
Keywords :
antiferromagnetic materials; boron alloys; cobalt alloys; iron alloys; magnetic anisotropy; magnetic storage; magnetic switching; magnetic thin film devices; magnetic thin films; magnetic tunnelling; metallic thin films; oxidation; random-access storage; CoFeB; anisotropy; magnetic tunnel junctions; magnetization; oxidization; surface oxidation; switching-field variation; Anisotropic magnetoresistance; Magnetic anisotropy; Magnetic field measurement; Magnetic films; Magnetic switching; Magnetic tunneling; Oxidation; Perpendicular magnetic anisotropy; Saturation magnetization; Shape; MRAM; MTJ; Magnetic thin film devices; nanomagnetics;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2007.893527
