CoFeAlB alloy with low damping and low magnetization as a candidate for spin transfer torque switching

We investigate the effect of Al doping on the magnetic properties of the CoFeB alloy. Comparative measurements of the saturation magnetization, the Gilbert damping parameter α, and the exchange constant as a function of the annealing temperature for CoFeB and CoFeAlB thin films are presented. Our results reveal a strong reduction of the magnetization for CoFeAlB in comparison to CoFeB. If the prepared CoFeAlB films are amorphous, the damping parameter α is unaffected by the Al doping in comparison to the CoFeB alloy. In contrast, in the case of a crystalline CoFeAlB film, α is found to be reduced. Furthermore, the x-ray characterization and the evolution of the exchange constant with the annealing temperature indicate a similar crystallization process in both alloys. The data prove that CoFeAlB fulfills the requirements to be considered an attractive candidate for spin torque switching purposes and a reduction of the switching current in comparison with CoFeB is expected.