Spin-valve heads in the current-perpendicular-to-plane mode for ultrahigh-density. recording

We have investigated the magnetoresistance properties of spin valves in the current-perpendicular-to-plane (CPP) mode. Conventional single spin-valve (SV) film shows resistance area product RA=81 m/spl Omega//spl mu/m/sup 2/, and resistance change area product /spl Delta/RA=0.35 m/spl Omega//spl mu/m/sup 2/. For a CPP element of a single SV with oxide layers, /spl Delta/RA dramatically increased to 9.0 m/spl Omega//spl mu/m/sup 2/. Micromagnetics simulation revealed that the readback performance of the CPP head with low-impedance conventional SV film was much affected by sense current. On the other hand, the medium impedance CPP head, such as the SV film with oxide layers, shows several advantages compared with the low impedance head, such as higher output voltage, less influence by magnetic field of the sense current, and narrower core width.