Energy barrier measurement and optimization in exchange coupled FePt/TiO2 nano-composite thin films

• Published in: Journal of magnetism and magnetic materials Vol. 331; pp. 187 - 192
• Main Authors: Zhou, Tie-Jun, Cher, K.M., Lwin, Phyoe Wai, Hu, J.F.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2013; Elsevier
• Subjects: Anisotropy graded media; Barriers; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Energy barrier; Exact sciences and technology; Exchange and superexchange interactions; Exchange-coupled-composite media; FePt; Ferrous alloys; Figure of merit; Interlayers; Iron compounds; Joining; Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Nanostructure; Physics; Stoner–Wohlfarth (S–W) model; Thin films; Titanium dioxide; FePt; Stoner–Wohlfarth (S–W) model; Exchange-coupled-composite media; Anisotropy graded media; Energy barrier; Platinum alloys; Magnetic moments; Iron alloys; Switching; Thin films; Thickness; Stoner-Wohlfarth (S-W) model; Composite materials; Stoner model; Nanocomposites; Anisotropy; Titanium oxide; Figure of merit; Exchange interactions; Bilayers
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2012.11.044

The 45-degree method is firstly applied to measure the energy barrier of FePt/TiO2 nanocomposite thin films with hard layer only and with hard–soft coupled bilayers. It was experimentally demonstrated that energy barrier measured using 45-degree method is more reliable than that measured using the conventional method with which the field is applied along the film normal. It is found that the energy barrier of bilayer films decreases with soft layer thickness, while the interlayer exchange coupling has little effects on the energy barrier. Both soft layer thickness and interlayer coupling strength have a strong effect on the figure of merit. Decrease in interlayer coupling firstly increases the figure of merit, while, too much reduction of coupling results in the appearance of 2-step switching and therefore decreasing in figure of merit. ► We experimentally demonstrate a more reliable way to measure the energy barrier of advanced media. ► 5° method is more accurate than the conventional method. ► Insensitivity of Hsw against field angle at 45° might account for the observed higher reliability. ► The energy barrier of ECC media decreases with soft layer thickness. ► The interlayer exchange coupling has little effects on the energy barrier.