Analysis on Giant Magnetoresistive Characteristics of Synthetic Antiferromagnet-Based Spin Valves with Modified Pinned Layers

A parametric sensitivity analysis has been performed on a new type of synthetic antiferromagnet-based spin valves (SSVs) comprising a modified pinned structure using CoFe (P1)-Ru-CoFe (P2)-Ru-CoFe (P3). Recently, it was demonstrated that this type of modified synthetic spin valves (MSSVs) could deliver larger effective exchange field (H_ex.eff) as well as better bias point control capability over a conventional SSV, in particular, when the device size became as small as 50 nm. A series of calculations based on the Landau-Lifschitz-Gilbert equation incorporating a single-domain multilayer model was carried out. We considered three key parameters such as an indirect exchange coupling energy ( J₁) between P1-P2 as well as P2-P3, an exchange biasing energy between P1 and antiferromagnetic layer (J_eb), and a relative giant magnetoresistive contribution (R) due to the angular difference of magnetizations in the pinned structure. It was found that J ₁ was mainly related with the saturation field (H_s) and the field at which the maximum subpeak magnetoresistance (MR) ratio (H _sub) occurred, while J_eb influenced on the H _ex.eff. R raised the MR ratio between the main peak and subpeak. As J₁ increased, H_ex.eff also increased. As the cell dimension decreased below 1 μm, H_ex.eff and H_s increased while H_sub decreased rapidly.