doi:10.1016/j.actamat.2019.05.035engPablo-Navarro, JavierWinkler, RobertHaberfehlner, GeorgMagen, CésarPlank, HaraldTeresa, José María deIn situ real-time annealing of ultrathin vertical Fe nanowires grown by focused electron beam induced depositionART-2019-113062Focused Electron Beam Induced Deposition is a consolidated technique for the growth of three-dimensional (3D) nanostructures. However, this single-step nanofabrication method requires further efforts to optimize simultaneously dimensional and compositional properties, in particular for deposits with a high aspect ratio. More specifically, ferromagnetic 3D nanowires (NWs) with diameters in the sub-50 nm regime and high metallic contents up to 95 at. % attract great interest to improve the final performance of magnetic nanodevices such as magnetic tips for scanning probe microscopy. In this work, we report on real-time monitoring during chemical purification and structural crystallization processes of ultra-narrow 3D Fe NWs (<50 nm in diameter achieved) by post-growth in situ annealing in a transmission electron microscope. NW heating up to 700 degrees C in very high vacuum reveals the local increase of the metallic content along the entire NW length concomitant with the growth of large Fe single crystals from initially amorphous compounds. A metallic purity of 95 at. % is observed in several regions, dramatically boosting the initial Fe content of 40 at. %. The real-time in situ tracking of 3D nanostructures during thermal annealing is a key element to design and optimize novel purification processes for the fabrication of customized components to be integrated in spintronic, logic and sensing devices. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.2019http://zaguan.unizar.es/record/13095310.1016/j.actamat.2019.05.035http://zaguan.unizar.es/record/130953oai:zaguan.unizar.es:130953info:eu-repo/grantAgreement/ES/DGA/E13-17Rinfo:eu-repo/grantAgreement/EC/H2020/823717/EU/Enabling Science and Technology through European Electron Microscopy/ESTEEM3This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 823717-ESTEEM3info:eu-repo/grantAgreement/ES/MINECO/MAT2017-82970-C2-1-Rinfo:eu-repo/grantAgreement/ES/MINECO/MAT2017-82970-C2-2-RActa Materialia 174 (2019), 379-386by-nc-ndhttp://creativecommons.org/licenses/by-nc-nd/3.0/es/info:eu-repo/semantics/openAccess