Crystal Growth and magnetic Domain Structure in CoCr Sputtered Films

Abstract

Crystal growth is investigated in CoCr films sputtered with applying negative substrate bias voltage V_B. Saturation magnetization and perpendicular magnetic anisotropy decrease with increasing V_B which comes from more uniform mixing of Co and Cr. Crystal growth is enhanced by applying about -75V bias accompanying an increment of c-axis orientation. Different shape in magnetic hysteresis loop between zero bias films in which Cr segregates around columns and -75 V bias films including grownup crystals suggests different mode in the magnetization process. Magnetic domain structure is observed by Bitter technique in the two types of CoCr films in which magnetization process is thought to be a rotational mode and a wall displacement mode. However, Bitter pattern is the same and composed of dotted contrast in the both films suggesting that the magnetization localizes in the columns.