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

In this paper, junctions with reduced H/sub 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/sub f/ and coercivity when compared with CoFe. Junctions processed down to 2/spl times/4...

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Bibliographic Details
Published in:IEEE transactions on magnetics 2004-07, Vol.40 (4), p.2272-2274
Main Authors: Cardoso, S., Ferreira, R., Freitas, P.P., MacKenzie, M., Chapman, J., Ventura, J.O., Sousa, J.B., Kreissig, U.
Format: Article
Language:English
Subjects:
Amorphous materials
Chemical analysis
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Electrodes
Exact sciences and technology
Ion beams
Magnetic analysis
Magnetic films
Magnetic properties and materials
Magnetic tunneling
Magnetism
Optical coupling
Oxidation
Physics
Tunneling magnetoresistance
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Summary:In this paper, junctions with reduced H/sub 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/sub f/ and coercivity when compared with CoFe. Junctions processed down to 2/spl times/4 /spl mu/m/sup 2/ with 40-thick CoFeB bottom electrodes have 42% of tunneling magnetoresistance (TMR), (R/spl times/A/spl sim/400 /spl Omega/./spl mu/m/sup 2/), H/sub c/ of /spl sim/10 Oe and H/sub f/ of /spl sim/2 Oe. CoFe-based junctions (R/spl times/A/spl sim/500 /spl Omega/./spl mu/m/sup 2/) have lower TMR (/spl sim/35%) and larger H/sub f/ (/spl sim/5-6 Oe) and H/sub c/ (/spl sim/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.
ISSN:0018-9464
1941-0069
DOI:10.1109/TMAG.2004.832147