131537 20240212142201.0 doi 10.1039/c9nr08557b sideral 116481 ART-2020-116481 eng Martínez-Pérez, M. J. Universidad de Zaragoza (orcid)0000-0002-8125-877X Magnetic vortex nucleation and annihilation in bi-stable ultra-small ferromagnetic particles 2020 Vortex-mediated magnetization reversal in individual ultra-small (~100 nm) ferromagnetic particles at low temperatures is studied by nanoSQUID magnetometry. At zero applied bias field, the flux-closure magnetic state (vortex) and the quasi uniform configuration are bi-stable. This stems from the extremely small size of the nanoparticles that lies very close to the limit of single-domain formation. The analysis of the temperature-dependent (from 0.3 to 70 K) hysteresis of the magnetization allows us to infer the nature of the ground state magnetization configuration. The latter corresponds to a vortex state as also confirmed by electron holography experiments. Based on the simultaneous analysis of the vortex nucleation and annihilation data, we estimate the magnitude of the energy barriers separating the quasi single-domain and the vortex state and their field dependence. For this purpose, we use a modified power-law scaling of the energy barriers as a function of the applied bias field. These studies are essential to test the thermal and temporal stability of flux-closure states stabilized in ultra-small ferromagnets. © 2020 The Royal Society of Chemistry. info:eu-repo/semantics/closedAccess All rights reserved http://www.europeana.eu/rights/rr-f/ 7.79 2020 MATERIALS SCIENCE, MULTIDISCIPLINARY 62 / 333 = 0.186 2020 Q1 T1 PHYSICS, APPLIED 23 / 160 = 0.144 2020 Q1 T1 CHEMISTRY, MULTIDISCIPLINARY 32 / 178 = 0.18 2020 Q1 T1 NANOSCIENCE & NANOTECHNOLOGY 29 / 106 = 0.274 2020 Q2 T1 2.037 2020 Nanoscience and Nanotechnology 2020 Q1 Materials Science (miscellaneous) 2020 Q1 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Müller, B. Lin, J. Rodriguez, L. A. Snoeck, E. Kleiner, R. Sesé, J. Universidad de Zaragoza (orcid)0000-0002-7742-9329 Koelle, D. 2003 395 Universidad de Zaragoza Dpto. Física Materia Condensa. Área Física Materia Condensada 12, 4 (2020), 2587-2595 Nanoscale Nanoscale 2040-3364 https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078693198&doi=10.1039%2fc9nr08557b&partnerID=40&md5=f5f3825afdb6a582b3740ef6e3ed741f Texto completo de la revista 2566605 http://zaguan.unizar.es/record/131537/files/texto_completo.pdf Versión publicada 2935413 http://zaguan.unizar.es/record/131537/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:131537 articulos driver 2024-02-12-13:54:35 ARTICLE