CoFe/Cu多層膜のCPP (Cur rent Perpendicular to the Plane)-GMR特性  [in Japanese] Gianat Magnetoresistance Properties of a CoFe/Cu multilayer in CPP (Current Perpendicular to the Plane) Geometry  [in Japanese]

Multilayer GMR films have a larger MR ratio than spin-valve films and, therefore, have great potential for use as read sensors in HDD (hard disk drive) heads for ultra-high-density recording. Moreover, the MR ratio of multilayer GMR films is twice as large when the sense current flows perpendicular to the plane (CPP) than when it flows in the plane (CIP). We investigated the GMR properties of CPP elements of a Co_<0.9>Fe_<0.1>/Cu multilayer in a structure where the GMR film is under the top terminal layer and connected to the bottom terminal layer through a micron-sized contact hole. An MR ratio of 13.1% and saturation field (H_s) of 150 Oe were obtained. The field sensitivity of 0.1%Oe was much larger than that of CIP elements. The value of H_s of the CPP elements was almost constant as a function of the element dimensions, because the demagnetization field was insensitive of the sensor size in our CPP element structure and small enough even for submicron elements.