New approaches to spin valve head materials and its future trends

This paper will discuss materials for future GMR heads for high-density recording. Here we report a self-compensated dual spin valve and a dual spin valve with synthetic antiferromagnetic layers. The self-compensated spin valve has a Delta R/R of 8.3% and the dual spin valve with synthetic antiferromagnetic layers has a Delta R/R of 13%. Because of the nature of the self-compensation of the moments in pinned layers, both structures are thermally stable and reliable. Spin valve heads fabricated with these structures have low asymmetry in their read-back signals. The synthetic antiferromagnetic layer displays many interesting properties. It has a high saturation field for Ru thicknesses ranging from 5 to 9 Angstrom. It has a small net moment. If it is pinned by an antiferromagnetic film, only a small exchange energy is needed to provide a high exchange bias for the pinned layer, hence its application can be extended to higher temperatures. For ultra high recording purposes, spin dependent tunneling (SDT) devices may serve as one of the candidates for ultra-high density recording sensors.