Deposition rate dependence of coercivity in vaccum evaporated CoCr films

Deposition rate dependence of perpendicular coercivity Hcl in Cocr evaporated films at the deposition rate ranging from 0.4nm/s to 400nm/s is studied. Hcl increases with decreasing deposition rate as well as with increasing substrate temperature. A High Hcl over 500 Oe, which has ever been obtained only at a substrate temperature over 250°C when deposition rate is high(400nm/s), is obtained at a substrate temperature of 150°C under deposition rate of 2nm/s. "Shoulder" in the hysteresis loop disappears as Hcl exceeds 400 Oe. Therefore to decrease the deposition rate and to increase the substrate temperature have the same effect on Hcl. Saturation magnetization of the films with the same Cr concentration increases with decreasing deposition rate, and it is suggested that the degree of Cr segregation increases with decreasing deposition rate. Hcl is independent of the background pressure when the relative pressure, the quotient of (background pressure/deposition rate), is between 2×10^-8and 5×10^-6torr/(nm/s). From the results above, it is clarified that the difference of deposition rate between vacuum evaporation and sputtering is one of the major reasons for the difference of Hcl between the two.