Thermal stability of spin valves using amorphous CoFeB

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 degrees C. After annealing at 300 degrees C, it became fee-like. The MR ratio of NiO/CoFeB(2 nm)/Cu(2 nm)/CoFeB(6 nm) increased from Lt to about 8% after annealing at 300 degrees C, while that of Co(2 nm)/Cu(2 nm)/CoFeB(4 nm) increased from 6 to about 10%.