Effects of the structural parameters including surface roughness, on the properties of Co/Pt multilayered films

Abstract

Co/Pt multilayered films were prepared by using alternate deposition with two electron-beam sources in a physical-vapor-deposition system. When the Pt sublayer and buffer-layer thicknesses were fixed to be 10 Å and the Co sublayer thickness was varied, a measurement of the perpendicular magnetic anisotropy constants showed that the transition from in-plane to perpendicular magnetic anisotropy took place at a Co sublayer thickness of 4 Å. As the Co sublayer thickness increased, the saturation Kerr-rotation angle also increased, but the remanence Kerr-rotation angle decreased, as shown by the sheared Kerr-rotation hysteresis loops. When the Co and Pt sublayers were fixed to be 3 Å and 10 Å, respectively, and the Pt buffer-layer thickness was varied, the film roughness increased with the buffer-layer thickness owing to an increase in buffer-layer roughness. The coercivity increased and the saturation magnetization decreased with the roughness because more defects were present. Although the Kerr-rotation angle was expected to become larger with the roughness which would have resulted in an enhancement of induced magnetic polarization of the neighboring Pt atoms by the Co atoms, the Kerr-rotation angle turned out to be smaller owing to a further reduction in the saturation magnetization. The effective magnetic anisotropy increased with the Pt buffer-layer thickness up to 200 Å, but a further increase in buffer-layer thickness caused the effective magnetic anisotropy to decrease.