In situ grazing-incidence small-angle X-ray scattering observation of block-copolymer templated formation of magnetic nanodot arrays and their magnetic properties

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• 作者：Andreas Meyer ; Norbert Franz ; Hans Peter Oepen ; Jan Perlich…
• 关键词：poly(styrene) ; b ; poly(vinyl pyridine) ; argon ion etching ; self ; assembly ; grazing ; incidence small ; angle X ; ray scattering (GISAXS) simulation ; magnetic nanodot coercivity
• 刊名：Nano Research
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：10
• 期：2
• 页码：456-471
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Nanotechnology; Materials Science, general; Atomic/Molecular Structure and Spectra; Condensed Matter Physics; Biotechnology; Biomedicine, general;
• 出版者：Tsinghua University Press
• ISSN：1998-0000
• 卷排序：10

文摘

The fabrication of bit-patterned media (BPM) is crucial for new types of hard disk drives. The development of methods for the production of BPM is progressing rapidly. Conventional lithography reaches the limit regarding lateral resolution, and new routes are needed. In this study, we mainly focus on the dependence of the size and shape of magnetic nanodots on the Ar+-ion etching duration, using silica dots as masks. Two-dimensional (2D) arrays of magnetic nanostructures are created using silica-filled diblock-copolymer micelles as templates. After the self-assembly of the micelles into 2D hexagonal arrays, the polymer shell is removed, and the SiO₂ cores are utilized to transform the morphology into a (Co/Pt)2-multilayer via ion etching under normal incidence. The number of preparation steps is kept as low as possible to simplify the formation of the nanostructure arrays. High-resolution in situ grazing-incidence small-angle X-ray scattering (GISAXS) investigations are performed during the Ar+-ion etching to monitor and control the fabrication process. The in situ investigation provides information on how the etching conditions can be improved for further ex situ experiments. The GISAXS patterns are compared with simulations. We observe that the dots change in shape from cylindrical to conical during the etching process. The magnetic behavior is studied by utilizing the magneto-optic Kerr effect. The Co/Pt dots exhibit different magnetic behaviors depending on their size, interparticle distance, and etching time. They show ferromagnetism with an easy axis of magnetization perpendicular to the film. A systematic dependence of the coercivity on the dot size is observed.