Ferromagnetic coupling field reduction in CoFeB tunnel junctions deposited by ion beam

Author

Cardoso, Susana ; Ferreira, Ricardo ; Freitas, Paulo P. ; MacKenzie, Maureen ; Chapman, John ; Ventura, João O. ; Sousa, João B. ; Kreissig, Ulrich

Author_Institution

Inst. de Engenharia de Sistemas e Computadores, Lisbon, Portugal

Volume

40

Issue

4

fYear

2004

fDate

7/1/2004 12:00:00 AM

Firstpage

2272

Lastpage

2274

Abstract

In this paper, junctions with reduced H_f coupling were fabricated by ion beam deposition and oxidation, using CoFeB electrodes. The CoFeB layer has a strong (111) texture that can be the origin of lower H_f and coercivity when compared with CoFe. Junctions processed down to 2×4 μm² with 40-thick CoFeB bottom electrodes have 42% of tunneling magnetoresistance (TMR), (R×A∼400 Ω.μm²), H_c of ∼10 Oe and H_f of ∼2 Oe. CoFe-based junctions (R×A∼500 Ω.μm²) have lower TMR (∼35%) and larger H_f (∼5-6 Oe) and H_c (∼12-14 Oe). Local chemical composition analysis of the cross section indicated Fe-O segregation with very little Co grown on top of the barrier for CoFe-based junctions and not for CoFeB ones.

Keywords

boron alloys; cobalt alloys; ferromagnetic materials; ion beam assisted deposition; iron alloys; magnetic tunnelling; tunnelling magnetoresistance; CoFe-based junctions; CoFeB; CoFeB electrodes; CoFeB tunnel junctions; Fe-O segregation; chemical composition analysis; ferromagnetic coupling field reduction; ion beam deposition; ion beam oxidation; low ferromagnetic coupling; reduced Hf coupling; tunneling magnetoresistance; Amorphous materials; Chemical analysis; Electrodes; Ion beams; Magnetic analysis; Magnetic films; Magnetic tunneling; Optical coupling; Oxidation; Tunneling magnetoresistance; CoFeB electrodes; ion beam deposition; low ferromagnetic coupling; tunnel junctions;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2004.832147

Filename

1325475