The Effect of Spreading Resistance on the Magnetoresistance of Current-Perpendicular-to-Plane Spin Valves With Patterned Layers

We derived the magnetoresistance (MR) that takes into consideration the effect of spreading resistance (SR) due to the patterned layer in a spin-valve (SV) structure. Our analysis is based on the: 1) spin drift diffusion (SDD) model and 2) finite-element Poisson (FEP) solver. The SDD model does not take into consideration the effect of SR due to patterning, whereas FEP includes the effect of SR. This enables us to compare and analyze the contribution of both patterning and SR to the MR of the device. In a FM-NM-FM structure, the NM layer was patterned into: 1) single and 2) multiple cylindrical structure. We found that the spacer patterning and the resulting SR causes a significant increase (by >50%) of MR at low area ratio (A_R) of the patterned layer. Yet, MR of patterned structure is lower compared to the MR of original structure. However, patterning of a FM layer inserted within the NM spacer results in significantly higher MR