Unshielded spin valve heads exchange biased by synthetic antiferromagnets

This paper discusses the advantage of utilizing a Co/Ru/Co synthetic antiferromagnet in the fabrication of spin valve heads suitable for high density magnetic recording. Benefits of using the synthetic antiferromagnet are: (1) the pinning field is over 6000 Oe; (2) magnetic stability is achieved over a wide temperature range with the sensor well biased at temperatures as high as 250 degrees C, because the pinning field is still higher than 3000 Oe at this temperature; (3) the pinned layer biasing mechanism is enhanced as the sensor height is reduced, and a 7.2% change in the resistivity is observed in a sensor with a 0.5 mu m height and a 0.7 mu m trackwidth; (4) the free layer bias state is easily attainable in sensors with small height (< 1 mu m), as a consequence of the particular magnetic configuration of the synthetic antiferromagnet, which promotes an almost vanishing magnetostatic field; and (5) the sensor is only 17 nm thick.