Hard magnetic properties of sputtered Co and Co-P films

Both magnetic properties and microstructure of sputtered Co and Co-4.8 wt% P films ( ≈ 3000 Å) deposited near room temperature are studied as a function of Ar pressure P_Ar ranging from 4×10^-3 to 1.4×10^-1 Torr. The coercive force H_c of the film is a strong function of P_Ar. The coercive force of Co increases from 25 to 270 Oe with increasing P_Ar. With an addition of phosphorus in Co, H_c increases substantially. At high P_Ar ( ≈ 1×10^-1 Torr), a high H_c of 700 Oe and a low squareness of 0.58 are obtained. From observation of the microstructure, it is concluded that the structure of columns is responsible for the high H_c and the low squareness.