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We report the synthesis and characterization of size-tunable MnxFe3-xO4 ferrite nanoclusters of different sizes ranging from ~30 to ~120 nm. The nanoclusters synthesized via a hydrothermal polyol process show high crystallinity and a narrow size distribution. The magnetic properties of the nanoclusters demonstrate well-behaved magnetization and low-coercivity characteristics, ferrimagnetically at a large size, and superparamagnetically at a small size. [ABSTRACT FROM AUTHOR]

We report the efficiency of genomic DNA extraction as a function of particle size and quantity. For DNA extraction, we synthesized magnetic nanoclusters of various sizes and coated the surface of these magnetic nanoclusters with meso-2,3-dimercaptosuccinic acid. We showed that the nanoclusters had a tight particle size distribution and high crystallinity. Furthermore, we observed that the three types of magnetic nanoclusters studied exhibited ferrimagnetic behavior and that larger nanoclusters showed larger saturation magnetization values. The resultant efficiency of DNA extraction is inversely proportional to particle size in the range of nanoclusters tested, due to the fact that the surface-to-volume ratio decreases as particle size increases. [ABSTRACT FROM AUTHOR]

We have investigated the effect of external magnetic field exercised during the fabrication of the Co and Co/Cu multilayer nanowires in anodic aluminum oxide (AAO) templates using pulse electrodeposition. It is found that the effect becomes significant when the pore size is small. Deterioration occurs in the magnetic properties for the Co nanowires studied, whereas a distinct enhancement in the magnetic properties for the Cu/Co multilayer nanowires is achieved by applying an external magnetic field during nanowire growth using the AAO template comprising pores of 50 nm diameter. [ABSTRACT FROM AUTHOR]

The effect of substrates on the microstructure and magnetic properties of electrodeposited Co nanowire arrays in porous anodic aluminum oxide membrane was investigated. It is found that the nanowires possess dominant (002) and (110) textures on the Co-coated nanocrystalline Finemet™ and Au substrates, respectively. Magnetic measurements show that the easy axis of the nanowire arrays switches from perpendicular to the wire axis on Au to parallel to the wire axis on the Co-coated nanocrystalline Finemet™ substrate. [ABSTRACT FROM AUTHOR]

Interparticle interactions in magnetic nanoparticles are studied by dc and ac magnetization measurements. For non-interacting nanoparticles, while the anisotropy constant of the nanoparticles Keff = 1.6 × 105 erg/cm3 is accurately determined by fitting zero-field-cooled and field-cooled measurements, we show that Keff values deduced only from time relaxation measurements must require simultaneous adjustments of the complex susceptibility by taking into account the size distribution of nanoparticles. This leads to Keff = 1.7 × 105 erg/cm3 in agreement with dc measurements. For interacting nanoparticles, comparisons with theoretical models show that energies due to magnetic dipolar interactions can only be predicted for weak and moderate interactions. [ABSTRACT FROM AUTHOR]