Development of structural, magnetic, and transport properties in NiFe/Co-based top spin valve: Studies by sequential addition of constituent layers

Abstract

We have studied the structural variations in top spin valve (SV) structure Si(100)/SiOx/Nb(5 nm)/Ni80Fe20(4 nm)/Cu(3 nm)/Co (5 nm)/Fe50Mn50(10 nm)/Nb(5 nm) with respect to the number of layers sequentially deposited onto the substrate. Built-up samples (samples with different numbers of constituent layers in the SV structure described above) were deposited by dc magnetron sputtering. Specular x-ray reflectivity (XRR) was used to study the thickness and roughness of these samples. Simulation of XRR scans has been done, starting with samples consisting of fewer layers. Results obtained from these simulations were kept constant and utilized for the simulations of later samples. Such a strategy successfully yielded self-consistent results along the line of samples. M(H) measurements and four-point probe resistance measurements were also performed to probe the magnetic and transport properties of the samples. These results provided information for a simple analysis of the coupling between NiFe and Co layers across the Cu spacer, which is manifested as a loss of double coercivity in our pseudo- SV (Nb/NiFe/Cu/Co) sample.