GIANT MAGNETORESISTANCE AND ANTIFERROMAGNETICALLY COUPLED CO FRACTIONIN CO CU MULTILAYERS WITH VARYING NUMBER OF PERIODS/

The Giant Magnetoresistive signal of Co/Cu multilayers as a function o f the number N(Co) of Co layers is experimentally investigated for Cu thicknesses of 1 nm, i.e. in the 1 st antiferromagnetic maximum, and f or Co layer thickness of 1 nm. The stacks were deposited by DC magnetr on sputtering on an Fe buffer. The fraction F(AF) of the film that cou ples antiferromagnetically is derived from the hysteresis curves. A co rrection of F(AF) is required for the buffer and one Co layer. The F(A F) of stack periods close to the buffer is about 1, while F(AF) reduce s at large stack thicknesses. The GMR of stacks with small thicknesses is limited by the diffuse scattering at the outer surfaces. The GMR o f thicker stacks depends on F(AF) and the resistivity. Furthermore, th e meaning of F(AF) is discussed. By optimizing N(Co), we achieved DELT Arho/rho's as high as 72% at room temperature.