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Articles you may be interested inCo2MnGe-based current-perpendicular-to-the-plane giant-magnetoresistance spin-valve sensors for recording head applications J. Appl. Phys. 109, 093912 (2011); 10.1063/1.3563578 Structural characterization of nano-oxide layers in PtMn based specular spin valves J. Appl. Phys. 97, 10N706 (2005); 10.1063/1.1853872PtMn-based spin-dependent tunneling materials with thin alumina barrier fabricated by two-step natural oxidation Longitudinal bias method using a long distance exchange coupling field in tunnel magnetoresistance junctionsWe have investigated the use of ultrathin Al 2 O 3 barriers to fabricate low-resistance tunnel-valve sensors suitable for recording heads. Tunnel valves of the type underlayer/͑IrMn or PtMn͒/CoFe/ Al 2 O 3 /CoFe/NiFe/Cap layer have been fabricated by magnetron sputtering. Tunnel barriers are formed by Al metal deposition followed by in situ oxidation, and tunnel-junction test devices are built by photolithography with areas down to 1ϫ1 m 2 . Specific resistances as low as 13 ⍀ m 2 with 25% tunnel magnetoresistance have been obtained using Al thicknesses of 6-7 Å.

Using a combination of electron-beam lithography and Ar ion milling, we have fabricated spin-valve sensors with widths ranging from 30 to 250 nm. Although the resistance of the sensors scales as expected with width, the giant magnetoresistance ͑GMR͒ ratio decreases with decreasing width, consistent with the presence of a region with negligible GMR at the edges of the sensors. Sensors patterned using a focused ion beam showed a similar but much greater effect. We attribute this behavior to edge damage associated with the patterning process.

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