Interfacial and annealing effects on magnetic properties of CoFeB thin films

Abstract

The interfacial and annealing effects on magnetic properties of CoFeB thin films with Ta and Ru interfaces were investigated. It is found that the thickness of magnetically dead layer of as-deposited CoFeB film strongly depends on the interfaces. After annealing above 150°C boron atoms seem to diffuse out of CoFeB film and the effective saturation magnetization of CoFeB film increases with annealing temperature and annealing time. In addition, CoFeB film with Ta interfaces remains amorphous while that with Ru interfaces starts to crystallize during the annealing above 250°C. Furthermore, the annealing-induced anisotropy field of CoFeB film can be modified by using different seed and capping materials.