THERMAL-STABILITY OF SPIN VALVES USING AMORPHOUS COFEB

The thermal stability of spin valves consisting of amorphous CoFeB lay er(s) has been investigated. The structural properties were investigat ed by XRD and extended X-ray absorption spectroscopy for as-deposited and annealed films. The structure of CoFeB layer was confirmed amorpho us and stable up to about 250 degrees C. After annealing at 300 degree s C, it became fee-like. The MR ratio of NiO/CoFeB(2 nm)/Cu(2 nm)/CoFe B(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 abou t 10%.