Almeida T, McGrouther D, KovÁcs A, Dunin-Borkowski R, McVitie S
School of Physics and Astronomy, University of Glasgow, Glasgow, U.K.
Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Peter Grünberg Institute, Forschungszentrum Jülich, Jülich, Germany.
J Microsc. 2020 Sep;279(3):217-221. doi: 10.1111/jmi.12869. Epub 2020 Feb 6.
The growth of cobalt nanopatterns (NPs) using focused electron-beam induced deposition (FEBID) for localised magnetic studies is presented. The initial FEBID products are shown to be polycrystalline and form hetero-structured core-shell NPs through surface oxidation. Off-axis electron holography is performed to reconstruct their morphology, thickness profile and image their individual magnetic vortex domain states. In situ annealing to 400°C promoted migration of the Co-overspray to grow the Co NPs and improved their crystallinity through coarsening, as well as induced diffusion of embedded carbon out of their surface. It is found that the change in their morphology and chemical instability under heating restricts their suitability for examining thermally induced magnetic variations. LAY DESCRIPTION: In this paper, electron microscopy is used to deposit magnetic cobalt nanopatterns and characterise the effect of in-situ heating on their chemistry, structure and magnetic properties. The electron beam of the secondary electron microscope is used to dissociate an injected precursor gas near the SiN membrane substrate of in-situ transmission electron microscopy (TEM) chips and locally deposit the elemental Co in circular patterns ∼ 90 nm in diameter. TEM reveals formation of a Co-oxide shell and embedding of carbon from the precursor gas during growth. The technique of electron holography is used to image the magnetism of the core-shell Co / Co-oxide nanopatterns, which are shown to exhibit magnetic vortex states. In-situ annealing results in migration of the Co overspray to increase their height and carbon diffusion from their surface, as well as change in their original magnetic state through change of orientation. It is found that the change in the morphology and chemistry of Co nanopatterns under heating limits their use for studying the effect of temperature on their magnetism in isolation.
本文介绍了利用聚焦电子束诱导沉积（FEBID）生长钴纳米图案（NP）用于局部磁性研究的情况。结果表明，最初的FEBID产物为多晶，通过表面氧化形成异质结构的核壳NP。利用离轴电子全息术重建其形态、厚度分布，并对其单个磁涡畴态进行成像。在400°C下进行原位退火促进了钴过喷物的迁移，使钴NP生长，并通过粗化提高了其结晶度，同时还诱导了嵌入碳从其表面扩散出去。研究发现，加热时其形态和化学不稳定性的变化限制了它们用于研究热诱导磁变化的适用性。层次描述：在本文中，电子显微镜用于沉积磁性钴纳米图案，并表征原位加热对其化学、结构和磁性的影响。利用二次电子显微镜的电子束在原位透射电子显微镜（TEM）芯片的SiN膜基板附近离解注入的前驱体气体，并将元素钴局部沉积成直径约90nm的圆形图案。TEM显示在生长过程中形成了氧化钴壳层，并从前驱体气体中嵌入了碳。利用电子全息术对核壳钴/氧化钴纳米图案的磁性进行成像，结果表明它们呈现出磁涡态。原位退火导致钴过喷物迁移，增加其高度，碳从其表面扩散，以及通过取向变化改变其原始磁态。研究发现，加热时钴纳米图案的形态和化学变化限制了它们单独用于研究温度对其磁性影响的用途。
