Sperimagnetism in Perpendicularly Magnetized Co-Tb Alloy-Based Thin Films.

Thin films of Co1−xTbx (x = 0.10, 0.12, and 0.15) alloy have been prepared by a co-sputtering process using dc magnetron sputtering. The measurement of temperature variation of magnetization indicates that these films exhibit ferrimagnetism with Curie temperature (TC) much above the room temperature. The M–T curves under zero-field-cooled and field-cooled conditions indicate that Co0.85Tb0.15 film exhibits non-collinear sperimagnetic ordering due to competition between exchange interaction and perpendicular magnetic anisotropy. An increase of coercivity, squareness, and change of magnetic isotropy to magnetic anisotropy behavior with the increase of Tb composition was observed. Particularly, Co0.85Tb0.15 is found to exhibit perpendicular magnetic anisotropy. The relative reversal in these films follows the Kondorsky model. The post-annealing of the films helps to improve the squareness of the hysteresis curve, but it reduces the coercivity. [ABSTRACT FROM AUTHOR]