Effect of nano-oxide layers on giant magnetoresistance in pseudo-spin-valves using Co2FeAl electrodes

We studied the pseudo-spin-valves (PSVs) with a structure of Ta/Co2FeAl/NOL1/Co2FeAl/Cu/Co2FeAl/NOL2/Ta, where NOL represents the nano-oxide layer. Compared with the normal Co2FeAl (CFA) PSV with a structure of Ta/Co2FeAl/Cu/Co2FeAl/Ta, which shows only a current-in-plane (CIP) giant magnetoresistance (GMR) of 0.03%, the CFA PSV with NOLs shows a large CIP-GMR of 5.84%. The enhanced GMR by the NOLs inserted in the CFA PSV is due to the large specular reflection caused by [(CoO)(Fe2O3)(Al2O3)] in NOL1 and [(Fe2O3)(Al2O3)(Ta2O5)] in NOL2. Another reason is that the roughness of the interface between Ta and CFA is improved by the oxidation procedure.

Research highlights
► Nano-oxide layers are applied in the pseudo-spin-valves with the Heusler alloy.
► The CIP-GMR of pseudo-spin-valves is improved from 0.03% to 5.84%.
► The GMR ratio is decided by the position of nano-oxide layers.