Half-hedgehog spin textures in sub-100 nm soft magnetic nanodots
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
