Title :
Four-State Magnetoresistance in Epitaxial CoFe-Based Magnetic Tunnel Junctions
Author :
Uemura, Tetsuya ; Marukame, Takao ; Matsuda, Ken-ichi ; Yamamoto, Masafumi
Author_Institution :
Div. of Electron. for Informatics, Hokkaido Univ., Sapporo
fDate :
6/1/2007 12:00:00 AM
Abstract :
A four-state magnetic random access memory (MRAM) was developed using an epitaxial Co50Fe50-MgO-Co50Fe 50 magnetic tunnel junction (MTJ) with a tunnel magnetoresistance (TMR) ratio of 145% at room temperature (RT). Four remanent magnetization states in the single-crystalline Co50Fe50 electrode, due to the cubic anisotropy with easy axes of the lang110rang directions, result in four possible angular-dependent TMRs, each separated by more than 20% at RT. Analysis of the asteroid curve for Co50Fe50 indicated that the magnetic field along 22.5deg from the lang110rang directions made it possible to change the magnetization direction of the selected cell without disturbing those of the half-selected cells
Keywords :
cobalt alloys; electrodes; ferromagnetic materials; iron alloys; magnesium compounds; magnetic anisotropy; magnetic epitaxial layers; magnetic multilayers; magnetic storage; random-access storage; remanence; tunnelling magnetoresistance; 293 to 298 K; Co50Fe50-MgO-Co50Fe50; MRAM; angular-dependent TMR; asteroid curve; cubic anisotropy easy axes; epitaxial CoFe-based magnetic tunnel junctions; four-state magnetic random access memory; four-state magnetoresistance; magnetization direction; remanent magnetization states; single-crystalline electrode; tunnel magnetoresistance ratio; Electrodes; Iron; Magnetic anisotropy; Magnetic separation; Magnetic tunneling; Magnetization; Perpendicular magnetic anisotropy; Random access memory; Temperature; Tunneling magnetoresistance; CoFe; magnetic tunnel junction (MTJ); magnetoresistance (MR); multistate magnetic random access memory (MRAM);
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2007.893415
