Reduction of a coercive field without substantial current shunt by an additional CoFeB layer in GMR spin valve

The effects of an additional CoFeB layer to a CoFe free layer is investigated in a GMR spin valve. The GMR behavior as a function of t_f for the sample with and without the additional layer shows a similar tendency after thermal annealing at T = 275°C. The addition of CoFeB layer to the CoFe free layer seems to suppress the substantial current shunt which can be attributed to the high sensitivity of it. In particular, a higher sensitivity by 1.5 times is obtained on the free layer of CoFe/CoFeB compared to that normal spin-valve with CoFe free layer. This suggests that the coercivity of the sample with the additional layer is reduced with increasing t_f without critical current shunt.