Magnetic nanoparticles combined with natural protein fibres

Human hair and sheep wool are the natural protein fibres of complex structure, composed of Į-keratin chains are analyzed as basic components for the fabrication of nanomaterials. After carrying out some successful experiments in which we demonstrate that silver nanoparticles can be immobilized on the surface and inside hair and wool fibers [1, 2], we attempted to use another type of metal-containing nanoparticles and unite in one composite material such properties as superparamagnetism of iron oxide and nonmagnetism of natural protein fiber. The hair fibers, immersed in a reductant solution in order to break their surface disulfide groups, were placed in a Į-Fe2O3 – nanoparticle suspension while synthesis. After some time, the fiber surface took on a brown tinge. Hematite-containig nanoparti cles were found to penetrate not only into the hair cuticle but also into melanin granules inside the fibre volume. Electron magnetic resonance data (Varian Spectrometer, 9.1 GHz) indicates that the nanoparticles produced in the matrix are upeparamagnetic at room temperature. This interesting finding suggests that such a carrier can be associated with a magnetic bubble. The observed line width and effective g-factor are comparable to those reported for superparamagnetic iron oxide nanoparticles in a nonmagnetic matrix. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2065

Low temperature spin-glass magnetic behavior of Ce₃Pd₂₀Ge₆

A polycrystalline sample of Ce₃Pd₂₀Ge₆ is investigated using a dc SQUID magnetometer. A noticeable difference between ZFC and FC magnetic susceptibility is found below ≈60 K. The temperature dependence of the magnetic susceptibility demonstrates an anomaly near approximately 2.8K below which a remanent magnetic moment exists. Two characteristic temperatures detected support the assumption that there are different cerium magnetic subsystems in Ce₃Pd₂₀X₆ (X= Ge,Si) compounds. Unusual magnetic behavior observed in Ce₃Pd₂₀Ge₆ is discussed within the framework of the "molecular magnetism" model which predicts a frustration of exchange interactions

Magnetostatic interactions in planar ring-like nanoparticle structures

Numerical calculations of equilibrium state energies and local magnetic fields in planar ring-like nanoparticle structures were performed. The dipole–dipole, Zeeman and magnetic anisotropy interactions were included into the model. The result of their competition depends on the value of the external magnetic field, magnetic parameters of an individual nanoparticle, size and shape of the structures. Flux-closed vortexes, single domain, two- domain ‘‘onion’’-like, ‘‘hedgehog’’-like and more complex spin structures can be realized. The critical field, providing a sharp transition from the flux-closed vortex to the ‘‘onion’’-like state, can be regulated by a variation of the particle magnetization and anisotropy constant, their easy directions, and particle space arrangement