Magnetic dynamic properties of defective iron nanorings

Large-scale synthesis of single-crystalline iron oxide magnetic nanorings.

We present an innovative approach to the production of single-crystal iron oxide nanorings employing a solution-based route. Single-crystal hematite (alpha-Fe2O3) nanorings were synthesized using a double anion-assisted hydrothermal method (involving phosphate and sulfate ions), which can be divided into two stages: (1) formation of capsule-shaped alpha-Fe2O3 nanoparticles and (2) preferential ...

Cobalt ferrite nanorings: Ostwald ripening dictated synthesis and magnetic properties.

CoFe(2)O(4) nanorings were synthesized by a simple solvothermal process, in which Ostwald ripening was definitely responsible for the formation of hollow structures, and their ferromagnetic behavior at room temperature was observed.

Metastable states in magnetic nanorings

Magnetization states and hysteresis behavior of small ferromagnetic rings, of diameters 180–520 nm, have been investigated using magnetic force microscopy. In addition to the expected bi-domain ~‘‘onion’’! and flux-closed ~‘‘vortex’’! magnetization states, a metastable state has been found. This ‘‘twisted’’ state contains a 360° domain wall which can exist over a wide range of applied fields. F...

Optical properties of gold nanorings.

The optical response of ring-shaped gold nanoparticles prepared by colloidal lithography is investigated. Compared to solid gold particles of similar size, nanorings exhibit a redshifted localized surface plasmon that can be tuned over an extended wavelength range by varying the ratio of the ring thickness to its radius. The measured wavelength variation is well reproduced by numerical calculat...

Magnetic Cluster Expansion Model for High-Temperature Magnetic Properties of Iron and Iron-Chromium alloys