title: Exchange-coupled bimagnetic cobalt/iron oxide branched nanocrystal heterostructures.
abstract: A colloidal seeded-growth strategy, relying on time-programmed delivery of selected stabilizing surfactants, has been developed to synthesize bimagnetic hybrid nanocrystals (HNCs) that consist of a single-crystal tetrapod-shaped skeleton of ferrimagnetic (FiM) iron oxide functionalized with multiple polycrystalline spherical domains of ferromagnetic (FM) Co. Due to the direct bonding interfaces formed between the two materials at the relevant junction regions, the HNCs exhibit FiM-FM exchange coupling, which transcribes into a rich scenario of significantly modified properties (not otherwise achievable with any of the single components or with their physical mixtures), including higher saturation magnetization and coercitivity values, exchange biasing, and enhanced thermal stability due to induced extra anisotropy. The availability of these new types of HNCs suggests that development of appropriate synthetic tools for arranging distinct material domains in predetermined spatial arrangements could lead to a more rational design of nanoheterostructures potentially exploitable as active elements in future generations of magnetic recording devices.
authors.affiliation: Scuola Superiore ISUFI, University of Salento, Distretto Tecnologico ISUFI, via per Arnesano km 5, I-73100 Lecce, Italy.
authors.forename: Marianna
authors.initials: M
authors.lastname: Casavola
authors.forename: Andrea
authors.initials: A
authors.lastname: Falqui
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: García
authors.forename: Mar
authors.initials: M
authors.lastname: García-Hernández
authors.forename: Cinzia
authors.initials: C
authors.lastname: Giannini
authors.forename: Roberto
authors.initials: R
authors.lastname: Cingolani
authors.forename: P Davide
authors.initials: PD
authors.lastname: Cozzoli
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008280:Magnetics; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D005290:Ferric Compounds; D046911:Macromolecular Substances; C000499:ferric oxide; D003035:Cobalt