Perpendicular magnetic anisotropy and thermal stability in CoSiB/Pt multilayers

Abstract

The CoSiB/Pt multilayers with Pt buffer layer were successfully manufactured by magnetron sputtering technique on the Si substrate with 300 nm of SiO2. The optimal period of the CoSiB/Pt bilayer was 2. The thickness of CoSiB/Pt bilayer and Pt buffer layer were modulated. The perpendicular magnetic anisotropy (PMA) of each of the samples and thermal stability were studied by anomalous Hall effect (AHE) method. The best structure was Pt(1)/[CoSiB(0.5)/Pt(1)]2. The optimal thicknesses of Pt buffer layer and CoSiB/Pt bilayer in the periodic multilayer were 1, 0.5 nm and 1 nm, respectively. The XRD analysis, hysteresis loop measurement and a series of annealing treatment of the best sample were conducted. The results show that the sample has obvious (111)CoPt diffraction peak, forms a good (111) texture, enhanced interface coupling and good crystallinity. The effective magnetic anisotropy constant Keff of the sample is calculated to reach 5.11×104 J·m-3; when the annealing temperature is 200 ℃, the intensity of (111)CoPt diffraction peak of the sample is significantly enhanced, a strong (111) texture is formed at the interface, and the Keff reaches a maximum value of 1.0×105 J·m-3. When the annealing temperature is no more than 400 ℃, the sample can still maintain good PMA. Multilayer film sample structure Pt(1)/[CoSiB(0.5)/Pt(1)]2 has good PMA and thermal stability, and the suitable annealing temperature is conducive to improving the sample’s PMA.

Keywords

• cosib/pt multilayer
• anomalous hall effect
• perpendicular magnetic anisotropy
• effective magnetic anisotropy constant