Title :
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
fDate :
7/1/2004 12:00:00 AM
Abstract :
In this paper, junctions with reduced Hf 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 Hf 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), Hc of ∼10 Oe and Hf of ∼2 Oe. CoFe-based junctions (R×A∼500 Ω.μm2) have lower TMR (∼35%) and larger Hf (∼5-6 Oe) and Hc (∼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;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2004.832147
