Giant magnetoresistance in permalloy/copper multilayers

We report on giant magnetoresistance (GMR) and magnetization reversal process of face-to-face sputtered Ni83Fe17/Cu multilayers (Mls) with various sublayer thickness of copper (dCu) and permalloy (dPy). The maximum antiferromagnetic (AF) coupling and the GMR effect were found for samples with dCu about 1 nm and 2 nm. However, the dCu values corresponding to the largest field sensitivity of the GMR effect (S) were found to be different from those with the strongest AF exchange coupling. The maximum value of S about 0.6 %/Oe was obtained for Mls with dPy = 3.5 nm and dCu = 2.1 nm. it was also demonstrated that the Mls from the second AF coupling range (i.e., for dCu about 2 nm) show not only higher GMR field sensitivity but also higher thermal stability of the GMR than those from the first AF coupling range. (author)