2026-04-17T01:43:10Zhttps://recercat.cat/oai/request

oai:recercat.cat:2072/4358672026-03-13T05:24:25Zcom_2072_98col_2072_378192

00925njm 22002777a 4500 dc Varón Izquierdo, Miriam author Beleggia, Marco author Kasama, Takeshi author Harrison, R. J. author Dunin-Borkowski, Rafal E. author Puntes, Víctor author Frandsen, Cathrine author 2013 Magnetostatic (dipolar) interactions between nanoparticles promise to open new ways to design nanocrystalline magnetic materials and devices if the collective magnetic properties can be controlled at the nanoparticle level. Magnetic dipolar interactions are sufficiently strong to sustain magnetic order at ambient temperature in assemblies of closely-spaced nanoparticles with magnetic moments of ≥ 100â...μ B. Here we use electron holography with sub-particle resolution to reveal the correlation between particle arrangement and magnetic order in self-assembled 1D and quasi-2D arrangements of 15â...nm cobalt nanoparticles. In the initial states, we observe dipolar ferromagnetism, antiferromagnetism and local flux closure, depending on the particle arrangement. Surprisingly, after magnetic saturation, measurements and numerical simulations show that overall ferromagnetic order exists in the present nanoparticle assemblies even when their arrangement is completely disordered. Such direct quantification of the correlation between topological and magnetic order is essential for the technological exploitation of magnetic quasi-2D nanoparticle assemblies. Magnetic devices Magnetic properties and materials Nanoparticles Two-dimensional materials Dipolar magnetism in ordered and disordered low-dimensional nanoparticle assemblies