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This article belongs to the Special Issue Advances in Magnetic Force Microscopy. ; The fabrication of nanostructures with high resolution and precise control of the deposition site makes Focused Electron Beam Induced Deposition (FEBID) a unique nanolithography process. In the case of magnetic materials, apart from the FEBID potential in standard substrates for multiple applications in data storage and logic, the use of this technology for the growth of nanomagnets on different types of scanning probes opens new paths in magnetic sensing, becoming a benchmark for magnetic functionalization. This work reviews the recent advances in the integration of FEBID magnetic nanostructures onto cantilevers to produce advanced magnetic sensing devices with unprecedented performance. ; This research was funded by the Spanish Ministry of Economy and Competitiveness through the projects PID2020-112914RB-100, MAT2017-82970-C2-1-R, MAT2017-82970-C2-2-R and MAT2018-102627-T, BES-2015-072950, the Aragon Regional Government (Construyendo Europa desde Aragón) through the project E13_20R with European Social Fund funding. This work has received funding from the European's Union Horizon 2020 research and innovation programme under Grant No. 823717-ESTEEM3. ; Peer reviewed

Electron beam induced deposition of 3D cobalt nanowires with simultaneous high metallic content (≈80% at.) and small diameter (<100 nm) has been achieved by optimization of the growth parameters. Two different growth modes have been identified, denoted as radial and linear. In the radial mode, the wire diameter is at least ≈120 nm and the Co content is greater than ≈85% at. In the linear mode, the diameter is smaller than 80 nm and the Co content is at best ≈80% at. A sharp transition between both growth modes can occur inside a single nanowire for certain experimental conditions. Electron holography measurements indicate that in optimized Co nanowires the magnetic induction is high enough for applications in spintronics, magnetic sensing and actuation at the nanoscale. ; This work was supported by the Spanish Ministry of Economy and Competitivity through projects No. MAT2014-51982C2-1-R, MAT2014-51982C2-2-R and MAT2015-69725-REDT, including FEDER funds and by the Aragon Regional Government (Construyendo Europa desde Aragón) through project E26, with FEDER funding. This work was conducted within the framework of the COST Action CM1301 (CELINA). AFP acknowledges funding from a EPSRC Early Career Fellowship EP/M008517/1 and from a Winton Fellowship. In order to comply with EPSRC policy on research data, all metadata associated to this publication can be accessed via https://doi.org/10.17863/CAM.8106. JP-N grant is funded by the Ayuda para Contratos Predoctorales para la Formación de Doctores, Convocatoria Res. 05/06/15 (BOE 12/06/15) of the Secretaría de Estado de Investigación, Desarrollo e Innovación in the Subprograma Estatal de Formación of the Spanish Ministry of Economy and Competitiveness (MINECO) with the participation of the European Social Fund.

Electron beam induced deposition of 3D cobalt nanowires with simultaneous high metallic content (≈80% at.) and small diameter (<100 nm) has been achieved by optimization of the growth parameters. Two different growth modes have been identified, denoted as radial and linear. In the radial mode, the wire diameter is at least ≈120 nm and the Co content is greater than ≈85% at. In the linear mode, the diameter is smaller than 80 nm and the Co content is at best ≈80% at. A sharp transition between both growth modes can occur inside a single nanowire for certain experimental conditions. Electron holography measurements indicate that in optimized Co nanowires the magnetic induction is high enough for applications in spintronics, magnetic sensing and actuation at the nanoscale. ; This work was supported by the Spanish Ministry of Economy and Competitivity through projects No. MAT2014-51982C2-1-R, MAT2014-51982C2-2-R and MAT2015-69725-REDT, including FEDER funds and by the Aragon Regional Government (Construyendo Europa desde Aragón) through project E26, with FEDER funding. This work was conducted within the framework of the COST Action CM1301 (CELINA). AFP acknowledges funding from a EPSRC Early Career Fellowship EP/M008517/1 and from a Winton Fellowship. In order to comply with EPSRC policy on research data, all metadata associated to this publication can be accessed via https://doi. org/10.17863/CAM.8106. JP-N grant is funded by the Ayuda para Contratos Predoctorales para la Formación de Doctores, Convocatoria Res. 05/06/15 (BOE 12/06/15) of the Secretaría de Estado de Investigación, Desarrollo e Innovación in the Subprograma Estatal de Formación of the Spanish Ministry of Economy and Competitiveness (MINECO) with the participation of the European Social Fund. ; Peer reviewed

Using focused electron-beam-induced deposition, we fabricate a vertical, platinum-coated cobalt nanowire with a controlled three-dimensional structure. The latter is engineered to feature bends along the height: these are used as pinning sites for domain walls, which are obtained at remanence after saturation of the nanostructure in a horizontally applied magnetic field. The presence of domain walls is investigated using x-ray magnetic circular dichroism (XMCD) coupled to photoemission electron microscopy (PEEM). The vertical geometry of our sample combined with the low incidence of the x-ray beam produce an extended wire shadow which we use to recover the wire's magnetic configuration. In this transmission configuration, the whole sample volume is probed, thus circumventing the limitation of PEEM to surfaces. This article reports on the first study of magnetic nanostructures standing perpendicular to the substrate with XMCD-PEEM. The use of this technique in shadow mode enabled us to confirm the presence of a domain wall without direct imaging of the nanowire. ; This work was supported by Spanish Ministry of Economy and Competitivity through projects No. MAT2014-51982C2-1-R, MAT2014-51982C2-2-R and MAT2015-69725-REDT, including FEDER funds, and by the Aragon Regional Government (Construyendo Europa desde Aragón) through project E26, with FEDER funding. Javier Pablo-Navarro grant is funded by the Ayuda para Contratos Predoctorales para la Formación de Doctores, Convocatoria Res. 05/06/15 (BOE 12/06/15) of the Secretaría de Estado de Investigación, Desarrollo e Innovación in the Subprograma Estatal de Formación of the Spanish Ministry of Economy and Competitiveness (MINECO) with the participation of the European Social Fund. Michal Staňo acknowledges grant from the Laboratoire d'excellence LANEF in Grenoble (ANR10-LABX-51-01). ; Peer reviewed

Chirality plays a major role in nature, from particle physics to DNA, and its control is much sought-after due to the scientific and technological opportunities it unlocks. For magnetic materials, chiral interactions between spins promote the formation of sophisticated swirling magnetic states such as skyrmions, with rich topological properties and great potential for future technologies. Currently, chiral magnetism requires either a restricted group of natural materials or synthetic thin-film systems that exploit interfacial effects. Here, using state-of-the-art nanofabrication and magnetic X-ray microscopy, we demonstrate the imprinting of complex chiral spin states via three-dimensional geometric effects at the nanoscale. By balancing dipolar and exchange interactions in an artificial ferromagnetic double-helix nanostructure, we create magnetic domains and domain walls with a well-defined spin chirality, determined solely by the chiral geometry. We further demonstrate the ability to create confined 3D spin textures and topological defects by locally interfacing geometries of opposite chirality. The ability to create chiral spin textures via 3D nanopatterning alone enables exquisite control over the properties and location of complex topological magnetic states, of great importance for the development of future metamaterials and devices in which chirality provides enhanced functionality. ; This work was funded by EPSRC Early Career Fellowship EP/M008517/1, the Winton Program for the Physics of Sustainability, and the EU CELINA COST action. D.S.-H. acknowledges a Girton College Pfeiffer scholarship and support from the EPSRC CDT in Nanoscience and Nanotechnology. A.H.-R. and S.M.V. acknowledge funding from the EU Horizon 2020 program through Marie Skłodowska-Curie Action H2020-MSCA-IF-2016-74695. C.D. acknowledges funding from Leverhulme Trust (ECF-2018-016), Isaac Newton Trust (18-08), and a L'Oréal-UNESCO UK and Ireland Fellowship for Women in Science 2019. Funding by the Spanish Ministry of Science is acknowledged, grants MAT2017-82970-C2-1-R, MAT2017-82970-C2-2-R and MAT2018-102627-T, and by Aragon Government (Construyendo Europa desde Aragón), grant E13_20R including European Social Fund. J.P.-N. acknowledges MINECO funding BES-2015-072950. S.M.V. appreciates support from EPSRC EP/M024423/1. P.F. was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, Contract No. DE-AC02-05-CH11231 (NEMM program MSMAG). These experiments were performed at MISTRAL beamline at ALBA Synchrotron with the collaboration of ALBA staff and CALIPSOplus (Grant 730872) funding. ; Peer reviewed

(.) Funding by the Spanish Ministry of Science is acknowledged, grants MAT2017-82970-C2-1-R, MAT2017-82970-C2-2-R and MAT2018-102627-T, and by Aragón Government (Construyendo Europa desde Aragón), grant E13_20R including European Social Fund. J.P.-N. acknowledges MINECO funding BES-2015-072950. (.)

Topologically non-trivial structures such as magnetic skyrmions are nanometric spin textures of outstanding potential for spintronic applications due to their unique features. It is well known that Néel skyrmions of definite chirality are stabilized by the Dzyaloshinskii–Moriya exchange interaction (DMI) in bulk non-centrosymmetric materials or ultrathin films with strong spin–orbit coupling at the interface. In this work, we show that soft magnetic (permalloy) hemispherical nanodots are able to host three-dimensional chiral structures (half-hedgehog spin textures) with non-zero tropological charge. They are observed at room temperature, in absence of DMI interaction and they can be further stabilized by the magnetic field arising from the Magnetic Force Microscopy probe. Micromagnetic simulations corroborate the experimental data. Our work implies the existence of a new degree of freedom to create and manipulate complex 3D spin-textures in soft magnetic nanodots and opens up future possibilities to explore their magnetization dynamics. ; M. J., E. B., J. A. F. R and A. A. acknowledge the support from the Spanish Ministerio de Economia y Competitividad (MINECO) under projects no. S2018/NMT 4321, MAT2015-73775-JIN and MAT2016-76824-C3-1-R. E. B. acknowledges the financial support from the Alexander von Humboldt Foundation. M. G-G. and A.G-A. acknowledge the financial support from the Spanish MINECO project MAT2017-83632-C3 and from the Basque Government through IT1245-19 project and M. G. G. postdoctoral fellowship. M. J. also acknowledges financial support from the Spanish Ministry of Economy and Competitiveness, through The "María de Maeztu" Programme for Units of Excellence in R&D (MDM-2014-0377) and from Universidad Autónoma de Madrid and Comunidad Autónoma de Madrid through the project SI1/PJI/2019-00055. J. P.-N., C. M. and J. M. D. T. acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through Projects MAT2018-102627-T and MAT2017-82970-C2, and from the Aragon Regional Government (Construyendo Europa desde Aragón) through Project E13_20R, with European Social Fund funding. A grant to J. P.-N. was funded by the Ayuda para Contratos Predoctorales para la Formación de Doctores, Convocatoria Res. 05/06/15 (BOE 12/06/15) of the Secretaría de Estado de Investigación, Desarrollo e Innovación in the Subprograma Estatal de Formación of the Spanish Ministry of Economy and Competitiveness with the participation of the European Social Fund. K. G. acknowledges support by IKERBASQUE (the Basque Foundation for Science). The work of K. G. and O. C.-F. was supported by the Spanish Ministry of Economy and Competitiveness under the project FIS2016-78591-C3-3-R. ; Peer reviewed