Influence of Ga⁺ irradiation on microstructure and magnetic properties of CoFe film

The CoFe ferromagnetic film with substrate/seed Ta (5 nm)/Co₇₅Fe₂₅ (5 nm)/Cap Ta (8 nm) was prepared by using UHV magnetron sputtering. The Influence of Ga⁺ irradiation on the microstructure and the magnetic properties of CoFe film were investigated by means of transmission electron microscope (TEM), selected electronic diffraction (SAED) and X-ray diffraction (XRD). The concentration profiles for Ga, Ta in the film after irradiation were also simulated by SRIM2003. The results show that the coercivity and microstructure of the film vary slightly after irradiation at low dose (less than 1×10¹³ ion·cm^-2). With increasing of Ga⁺ ion dose, the coercivity decreases, the grain grows and the degree of <111> texture weakens. At high dose with 1×10¹⁵ ion·cm^-2, noncrystalline appears in the CoFe film due to the presence of large atoms such as Ta and Ga and the existence of large amount of vacancies resulting in the film non-magnetizaton.