Low-resistance IrMn and PtMn tunnel valves for recording head applications

We have investigated the use of ultrathin Al2O3 barriers to fabricate low-r esistance tunnel-valve sensors suitable for recording heads. Tunnel valves of the type underlayer/(IrMn or PtMn)/CoFe/Al2O3/CoFe/NiFe/Cap layer have b een fabricated by magnetron sputtering. Tunnel barriers are formed by Al me tal deposition followed by in situ oxidation, and tunnel-junction test devi ces are built by photolithography with areas down to 1 x 1 mum(2). Specific resistances as low as 13 Ohm mum(2) with 25% tunnel magnetoresistance have been obtained using Al thicknesses of 6-7 Angstrom. (C) 2001 American Inst itute of Physics.