Giant Magnetoresistance and Soft Magnetic Properties of NiFeCo/Cu Multilayers

Abstract

Giant magnetoresistance(GMR) and soft magnetic properties together with their structural characteristics were investigated for Ni₆₆Fe₁₆Co₁₈/Cu multilayers. The multilayers were prepared by the conventional rf sputtering method on glass or Si substrates using various buffer layers including Fe, NiFeCo, NiFe and CoZr. Although most of the multilayers exhibited (111) preferred orientation, Fe buffered multilayers showed a considerable (200) X-ray diffraction peak at Cu thicknesses around 1 nm and 2.2 nm which corresponded to the peak positions of GMR. By using fcc or amorphous underlayers the (200) diffraction intensity decreased while antiferromagnetic coupling strength was much reduced. Cross-sectional transmission electron micrograph revealed that the (100) oriented multilayer was grown on the (100) oriented Fe underlayer. By controlling the crystal orientation and the layer structure, significantly large magnetoresistance ratio of more than 10 % can be achieved in a field as low as 30 Oe.