A high temperature stable spin valve sensor head for high density applications

In this paper, we will report a read-only spin valve that has a trackwidth of 1.4 μm, a read gap of 0.23 μm, and with a stripe height of 0.75 μm. It had a corrosion resistant exchange pinning layer, Co₉₀Fe₁₀/FeMnRh, that provided an exchange bias of 225 Oe. It produces a very stable signal and a normalized amplitude of 1 mv/μm/(memu/cm²). Furthermore its asymmetry is lower that 6%. The ΔR/R of the spin valve film was 5.2% with the following structure: Ta(5 nm)/NiFe(2 nm)/Co₉₀Fe₁₀ (5 nm)/Cu(2.8 nm)/Co₉₀Fe₁₀(1.2 nm)/NiFe(2 nm)/FeMnRh(10 nm)/Ta(5 nm). The spin valve heads were soaked for 96 hours in a corrosion test chamber that was operated at a temperature of 85 C and a humidity of 85%. The sensor element, the exchange bias film, the hard magnetic longitudinal bias, and the conducting leads were free from corrosion after the corrosion test. Furthermore the spin valve read-only heads were electro-migration tested in an oven operated at 120°C, and the heads survived with the operating current up to 9 ma