CoCr thin films having a thickness from 0.014 μm to 0.5 μm were prepared by D.C. magnetron sputtering method using CoCr (18 wt% Cr) alloy target on PET film.
Thicker films are characterized on three zones which have different magnetic properties. In the first zone, films up to 0.03 μm thickness have very low coercive force Hc and small saturation magnetization Ms, and a poor vertical anisotropy. In the second zone from about 0.03 μm to 0.1 μm, Hc and Ms vary passing along the maximum value, but in this zone anisotropy field Hk is smaller than that of the third zone. In the third zone Hc gradually decreases with increasing film thickness, while Ms approaches a constant value and Ms reaches the highest constant value. TEM studies show CoCr films to have a fine columnar structure in thickness greater than 0.03 μm, and no changes in structure or diameter of the column have been observed in the 2 nd and 3 rd zones.
To investigate the effects of the underlayer, various kinds of metal were deposited on the PET film prior to CoCr deposition. Double layered CoCr films exhibit higher Hc than single layer and have poor crystalline orientation. SEM observation shows that CoCr films on the metallic underlayer have smaller grain size than do single layered films.
