Applied Surface Science, Vol.257, No.5, 1484-1486, 2010
Tunneling magnetoresistance in exchange-biased CoFeB/AlOx/Co/IrMn junctions
A series of exchange-biased magnetic tunneling junctions (MTJs) were made in an in-plane deposition field (h) = 500 Oe. The deposition sequence was Si(1 0 0)/Ta(30 angstrom)/CoFeB(75 angstrom)/AlOx(d angstrom)/Co(75 angstrom)/IrMn(90 angstrom)/Ta(100 angstrom), where d was varied from 12 angstrom to 30 angstrom. The MTJ was formed by the cross-strip method with a junction area of 0.0225 mm(2). The tunneling magnetoresistance (Delta R/R) of each MTJ was measured. The high-resolution cross-sectional transmission electron microscopic (HR X-TEM) image shows the very smooth interface and clear microstructure. X-ray diffraction (XRD) demonstrates that the IrMn layer of the MTJ exhibits a (1 1 1) texture. From the results (Delta R/R) increases from 17% to 50%, as d increases from 12 angstrom to 30 angstrom. The tunneling resistance (R-o) of these junctions ranges from 150 Omega to 250 Omega. The exchange-biasing field (H-ex) of the MTJ is 50-95 Oe. Finally, the saturation resistance (R-s) was measured as a function of the angle (alpha) of rotation, where alpha is the angle between h and the in-plane saturation field (H-s) = 1.1 kOe. The following figure presents the dependence of R-s on alpha, instead of originally expected independence, the curve actually varies with a period of pi. (C) 2010 Elsevier B.V. All rights reserved.
Keywords:Magnetic tunneling junction;Tunneling magnetoresistance;Tunneling resistance;Interfacial boundaries;Anisotropic phenomena