Tuning the Size, Shape and Density of γ′-GayFe4−yN Nanocrystals Embedded in GaN

Phase-separated semiconductor systems hosting magnetic nanocrystal (NCs) are attracting increasing attention, due to their potential as spintronic elements for the next generation of devices. Owing to their morphology- and stoichiometry-dependent magnetic response, self-assembled γ ’-Ga y Fe 4 − y N NCs embedded in a Fe δ -doped GaN matrix, are particularly versatile. It is studied and reported here, how the tuning of relevant growth parameters during the metalorganic vapour phase epitaxy process affects the crystalline arrangement, size, and shape of these self-assembled nanostructures. In particular, it is found that the Ga-flow provided during the δ -doping, determines the amount of Fe incorporated into the layers and the spatial density of the NCs. Moreover, the in-plane dimensions of the NCs can also be controlled via the Ga-flow, conditioning the aspect-ratio of the embedded nanostructures. These findings are pivotal for the design of nanocrystal arrays with on-demand size and shape, essential requirements for the implementation into functional devices.

Colloidal magnetic nanocrystal clusters: variable length-scale interaction mechanisms, synergetic functionalities and technological advantages

Magnetic particles of optimized nanoscale dimensions can be utilized as building blocks to generate colloidal nanocrystal assemblies with controlled size, well-defined morphology, and tailored properties. Recent advances in the state-of-the-art surfactant-assisted approaches for the directed aggregation of inorganic nanocrystals into cluster-like entities are discussed, and the synthesis parameters that determine their geometrical arrangement are highlighted. This review pays attention to the enhanced physical properties of iron oxide nanoclusters, while it also points to their emerging collective magnetic response. The current progress in experiment and theory for evaluating the strength and the role of intra- and inter-cluster interactions is analyzed in view of the spatial arrangement of the component nanocrystals. Numerous approaches have been proposed for the critical role of dipole-dipole and exchange interactions in establishing the nature of the nanoclusters’ cooperative magnetic behavior (be it ferromagnetic or spin-glass like). Finally, we point out why the purposeful engineering of the nanoclusters’ magnetic characteristics, including their surface functionality, may facilitate their use in diverse technological sectors ranging from nanomedicine and photonics to catalysis.

CuFe2O4 magnetic nanocrystal clusters as a matrix for the analysis of small molecules by negative-ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

CuFe2O4 MNCs were proposed as a new matrix for negative ion MALDI-TOF MS, which exhibited interference-free background, high salt tolerance and good reproducibility for analysis of small molecules.

One-pot synthesis of CuFe2O4 magnetic nanocrystal clusters for highly specific separation of histidine-rich proteins

A facile one-pot method was developed for the synthesis of CuFe2O4 magnetic nanocrystal clusters and their application in the ligand-free separation of histidine-rich proteins.