Thermal stability of spin valves using amorphous CoFeB

Abstract

The thermal stability of spin valves consisting of amorphous CoFeB layer(s) has been investigated. The structural properties were investigated by XRD and extended X-ray absorption spectroscopy for as-deposited and annealed films. The structure of CoFeB layer was confirmed amorphous and stable up to about 250°C. After annealing at 300°C, it became fcc-like. The MR ratio of NiO/CoFeB(2 nm)/Cu(2 nm)/CoFeB(6 nm) increased from 4 to about 8% after annealing at 200°C, while that of Co(2 nm)/Cu(2 nm)/CoFeB(4 nm) increased from 6 to about 10%.