Field induced anisotropy in amorphous Co_100−xTi_x thin films

Co_100−x Ti_x amorphous thin films were deposited by rf sputtering in the presence of a magnetic field applied parallel to the film plane. The deposition parameters were determined in order to obtain films with negligible perpendicular anisotropy K_p, small coercive field H_c, and a well‐defined in plane uniaxial anisotropy K_u. When the rf input power I_p is higher than a critical value, K_p is developed via a columnar structure, and for Ar pressure P_Ar higher than 3×10⁻³ Torr, H_c shows a large increases. Samples deposited under optimal conditions (I_p =100 W, P_Ar =3×10⁻³ Torr) present soft ferromagnetic properties and a large value of K_u, with 1.2×10⁴<K_u <2.5×10⁴ erg/cm³ for 7.5<x<16, K_u decreasing with decreasing Co content. The results suggest that K_u should be induced during the deposition process if one wants to obtain a large field induced anisotropy.