MR Enhancement in a Current Perpendicular-to-Plane Spin Valve by Insertion of a Ferromagnetic Layer Within the Spacer Layer

In this paper, we propose an alternative method to improve magnetoresistance by inserting a thin ferromagnetic (FM) layer into the nonmagnetic (NM) spacer of a basic spin-valve (SV) trilayer (FM1-NM-FM1), thus creating a penta-layer SV structure (FM1-NM-FM2-NM-FM1). We investigated the effect of increasing the resistivity (rho F2 ) of the FM2 on overall magnetoresistance (MR). We performed both analytical and numerical studies on the MR of the current perpendicular-to-plane (CPP) structure using the phenomenological spin drift-diffusion models. For finite rho F2 , the MR profile is dependent on the intrinsic conductance polarization (alpha F2 ) of FM2. We found that inserting FM2 enhances MR when alpha F2 exceeds a critical value of alpha 2C . It is found that MR can be doubled by inserting a FM layer with high alpha F2 , such as the half-metallic Cr 2 O. We have numerically calculated MR max and the corresponding rho F20 values for different alpha F2 values. Finally, we studied the effect of spin relaxation on the MR of the CPP SV