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

Volume

43

Issue

6

fYear

2007

fDate

6/1/2007 12:00:00 AM

Firstpage

2791

Lastpage

2793

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);

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2007.893415

Filename

4202953