Nano-oxide-layer specular spin valve heads with synthetic pinned layer: Head performance and reliability

To implement the specular nano-oxide-layer (NOL) spin valve (SV) heads for use in practical applications, it is key to simultaneously achieve a good specular effect of the NOL inserted in the synthetic ferrimagnet pinned layer (i.e., high magnetoresistance MR performance) and a strong pinning field through the NOL. By using CoFe+X as a substance to be subjected to oxidation, we obtained the NOL specular SV films simultaneously achieving a high MR ratio of 17%-18% and a high pinning field of 1100-1500 Oe. Narrow track (0.12 mum) heads were fabricated and they showed a high sensitivity of 10 mV/mum. Several reliability tests were done both at the sheet film level and the actual head level. The oxygen inside NOL was found to be stable up to 350 degreesC, and pinned layer magnetization canting after orthogonal field annealing was found to be almost the same as today's non-NOL SV films. An electrostatic discharge test and accelerated lifetime test were also performed and NOL specular heads were demonstrated to have almost the same robustness as today's non-NOL heads. (C) 2002 American Institute of Physics.