Large magnetoresistance in current-perpendicular-to-plane pseudo spin-valves using Co₂Fe(Ga_0.5Ge_0.5) Heusler alloy and AgZn spacer

Fully epitaxial pseudo spin-valves (PSVs) using 10-nm-thick Co₂Fe(Ga_0.5Ge_0.5) (CFGG) ferromagnetic layers and a 5-nm-thick AgZn space layer annealed at 630°C show a large current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) output with resistance-change area product, ΔRA, of 21.5 mΩ μm² and MR ratio of 59.6% at room temperature. These values are substantially enhanced to ΔRA of 59.8 mΩ μm² and MR ratio of 200.0% at 10K. The large MR is attributed to the high spin polarization of the CFGG electrodes with the enhanced L2₁ ordering induced by the atomic diffusion of Zn through the CFGG layers. The CPP-PSV shows relatively large ΔRA of 10.9mΩ μm² with the MR ratio of 25.6% for the low annealing temperature of 350°C, which is a practically useful feature for read sensor applications.