Exchange-coupled bimagnetic cobalt/iron oxide branched nanocrystal heterostructures.
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.
Casavola
Marianna
M
Scuola Superiore ISUFI, University of Salento, Distretto Tecnologico ISUFI, via per Arnesano km 5, I-73100 Lecce, Italy.
Falqui
Andrea
A
García
Miguel Angel
MA
García-Hernández
Mar
M
Giannini
Cinzia
C
Cingolani
Roberto
R
Cozzoli
P Davide
PD
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
D005290:Ferric Compounds; D046911:Macromolecular Substances; C000499:ferric oxide; D003035:Cobalt