title: Heterodimers based on CoPt3-Au nanocrystals with tunable domain size.
abstract: We describe an approach to synthesize colloidal nanocrystal heterodimers composed of CoPt(3) and Au. The growth is based on the nucleation of gold domains on preformed CoPt(3) nanocrystals. It is a highly versatile methodology which allows us to tune independently the size of the two domains in each dimer by varying several reaction parameters. The statistical analysis of the distribution of the domain sizes in the dimers and the compositional mapping achieved by dark field imaging and energy dispersive spectroscopy confirm that the two domains in each dimer are indeed made of CoPt(3) and Au, respectively. Structural characterization by high-resolution transmission electron microscopy shows that the two domains, both having cubic fcc Bravais lattice, can share a common {111}, {100}, or {110} facet, depending on the size of the initial CoPt(3) seeds. The magnetization measurements evidence a ferromagnetic CoPt(3) phase with a relatively low anisotropy as a consequence of their disordered crystalline structure, regardless of the presence of a Au tip. We believe that this prototype of nanocrystal dimer, which can be manipulated under air, can find several applications in nanoscience, as the Au section can be exploited as the preferential anchor point for various molecules, while the CoPt(3) domain can be used for magnetic detection.
authors.affiliation: National Nanotechnology Laboratory of CNR-INFM, Distretto Tecnologico ISUFI, 73100 Lecce, Italy. teresa.pellegrino@unile.it
authors.forename: Teresa
authors.initials: T
authors.lastname: Pellegrino
authors.forename: Angela
authors.initials: A
authors.lastname: Fiore
authors.forename: Elvio
authors.initials: E
authors.lastname: Carlino
authors.forename: Cinzia
authors.initials: C
authors.lastname: Giannini
authors.forename: P Davide
authors.initials: PD
authors.lastname: Cozzoli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ciccarella
authors.forename: Marc
authors.initials: M
authors.lastname: Respaud
authors.forename: Luca
authors.initials: L
authors.lastname: Palmirotta
authors.forename: Roberto
authors.initials: R
authors.lastname: Cingolani
authors.forename: Liberato
authors.initials: L
authors.lastname: Manna