Improved magnetic devices have been fabricated by replacing the
conventional seed layer (typically Ta) with a bilayer of Ru on Ta.
Although both Ru and Ta layers are ultra thin (between 5 and 20
Angstroms), good exchange bias between the seed and the AFM layer (IrMn
about 70 Angstroms thick) is retained. This arrangement facilitates
minimum shield-to-shield spacing and gives excellent performance in CPP,
CCP-CPP, or TMR configurations.