Domain Patterns of Co-Cr Sputtered Films with Low Coercivity

Co-Cr films were prepared on polyimide substrates at temperature TS=27°C by RF sputtering. The film thickness was varied from 0.2 ¿m to 2 ¿m. Films thus formed had low coercivity. When the c-axis orientation was good, reentrant perpendicular hysteresis loops could be obtained. In these films, we used the Bitter method to observe domain patterns as functions of the thickness h and the c-axis orientation ¿¿50. The stripe domains and wall motion could be observed clearly in thick films with good c-axis orientation. The relation between the stripe domain period D and the thickness h could be explained in terms of wall motion. The dependence of h and ¿¿50 on the squareness ratio of the in-plane hysteresis loop Mr(¿)/Ms were studied. We calculated the Mr(¿)/Ms versus ¿¿50 and h based on a model assuming the ¿* effect. Good agreement between experimental and calculated values was obtained.