Effects of an Fe Oxide 鬥-Layer on the Properties of Spin Valves

In this study, the effect of a delta-layer of Fe oxide to enhance the giant magnetoresistance (GMR) performance of spin valves is explored. The spin-valve films were deposited on a thermally oxidized Si wafer in an ultra-high-vaccum DC/RF magnetron sputtering system. Three structures of a spin valve were prepared: 1) a conventional spin valve (basic structure, CSV), 2) a bottom-specular type spin-valve (Type A), and 3) a double-specular type spin valve (Type B), respectively. The basic structure of the spin valve is Si/SiO₂ 2000/Ta 50/Ni₈₀Fe₂₀ 20/IrMn 60/PL (Co₉₀Fe₁₀ 30)/Cu 27/FL (Co₉₀Fe₁₀ 20/Ni₈₀Fe₂₀ 20)/Cu 10/Ta 50 (A), where PL and FL denote the pinned layer and the free layer, respectively. The Fe or Fe-oxide, and the Co₉₀Fe₁₀ or Co₉₀Fe₁₀-oxide delta-layer (4 kinds of a delta-layer) were inserted into the pinned layer for Type A and into both pinned and free layers for Type B. The Fe-oxide delta-layer was found to be very effective for enhancing the GMR properties including exchange bias.