Tunnel Magnetoresistance Properties of Double MgO-Barrier Magnetic Tunnel Junctions With Different Free-Layer Alloy Compositions and Structures

Author

Gan, Huadong ; Ikeda, Shoji ; Yamanouchi, Michihiko ; Miura, Katsuya ; Mizunuma, Kotaro ; Hayakawa, Jun ; Matsukura, Fumihiro ; Ohno, Hideo

Author_Institution

Center for Spintronics Integrated Syst., Tohoku Univ., Sendai, Japan

Volume

47

Issue

6

fYear

2011

fDate

6/1/2011 12:00:00 AM

Firstpage

1567

Lastpage

1570

Abstract

We investigated tunnel magnetoresistance (TMR) properties in double MgO-barrier magnetic tunnel junctions (DMTJs) with (Co₂₅Fe₇₅)_100-xB_x free-layers with x = 15, 20, and 25 (in at.%) sputtered at different power. The TMR ratio of DMTJs increased with sputtering power, which is ascribed to the B composition reduction in the CoFeB free-layer with increasing sputtering power. The x-ray diffraction measurement showed that crystallization into (001)-oriented texture of CoFeB film sandwiched between the two MgO-layers as well as an improvement of (001) orientation of top MgO-barrier are realized. The TMR ratio over 200% was obtained in DMTJs with a (Co₂₅Fe₇₅)₈₅B₁₅ free-layer sputtered at 0.88 and 1.77 W/cm².

Keywords

X-ray diffraction; boron alloys; cobalt alloys; crystallisation; iron alloys; magnesium compounds; magnetic multilayers; tunnelling magnetoresistance; (001)-oriented texture; (Co₂₅Fe₇₅)_100-xB_x free-layers; B composition reduction; CoFeB free-layer; MgO-(Co₂₅Fe₇₅)_100-xB_x-MgO; TMR ratio; X-ray diffraction; crystallization; double MgO-barrier magnetic tunnel junctions; free-layer alloy compositions; sputtering power; tunnel magnetoresistance properties; Annealing; Iron; Junctions; Magnetic tunneling; Sputtering; Tunneling magnetoresistance; MgO barrier; sputtering condition; tunnel magnetoresistance;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2010.2104137

Filename

5772191