The magnetic properties of core-shell-type nanoparticles with non-magnetic core and ferromagnetic shell are modeled using Monte Carlo simulation. The influence of the surface spin disorder on the magnetization and Curie temperature of magnetic states is studied. Due to competition between exchange coupling and surface anisotropy, rotation of the magnetization axis is observed, as the surface anisotropy of the ferromagnetic shell is increased. It

Relatively large iron oxide nanoparticles were synthesized by applying Pt assisted heterogeneous thermal decomposition of Fe(CO)5. HRTEM images and corresponding electron diffraction patterns revealed the appearance of a FePt3 core shifted from the center of each nanoparticle. The existence of smaller homogeneous nucleated nanoparticles due to iron excess was also evidenced. The high crystallization in a reverse spinel structure, most probably Fe3O4,

Fe / Fe3O4 (magnetite) powders obtained by ball milling at room temperature, undergo an incomplete redox reaction with formation of FeO. This reaction is favored due to the high energy developed during the milling and alloying. Concurrential effects of the milling, such as grain refinement down to the nanometric scale lead at the end of the milling processes to a mixed multiphased nanopowder, with a homogeneous dispersion of Fe and Fe oxide grains.

Systems composed of ferromagnetic – antiferromagnetic phases that exhibit exchange bias properties are of great importance for technological applications. We report a structural and magnetic study of nanopowders obtained by ball milling of a mixture of Fe and Fe3O4 at room temperature. Temperature-dependent X-ray diffraction studies show formation of wüstite (FeO) via an incomplete redox reaction during the milling. Wüstite co-exists in the as-milled

Exchange coupling between alternatively dispersed hard and soft magnetic phases, gives rise to exchange spring magnets with enhanced energy product (BH)max that are believed to represent a novel class of permanent magnets with improved properties. The synthesis of a hybrid nanocomposite system made of soft magnetic Fe3B melt spun ribbon and hard magnetic Fe-Pt thin film, obtained by e-beam co-deposition in ultrahigh vacuum onto the ribbons, is reported.

The magnetic properties of FINEMET-type nanocrystalline alloys and isolated ferromagnetic AgCo nanoparticles are investigated both experimentally and numerically. Theoretical models of spins that simulate ideal nanocrystalline alloys and isolated nanoparticles are considered while their magnetic properties are derived from Monte Carlo simulation of low-temperature spin ordering. Interesting features such as magnetic polarization of the matrix due

FexOy- SiO2 nanocomposites were prepared by sol-gel method by using two SiO2 sources and Fe(SO4)27H2O as raw materials. The amorphous gels were thermally treated up to 1000°C. The initial gel and the thermally treated samples were characterized by thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA) and infrared spectroscopy. The presence of hematite was confirmed by the obtained Mössbauer spectra which showed the characteristic

Temperature dependences of magnetization of core-shell-type nanoparticles with non-magnetic core and ferromagnetic shell are obtained using Monte Carlo simulation. The influence of surface spin disorder of the ferromagnetic shell on overall shape of magnetization curve is analyzed. The magnetic state diagram (in shell thickness - surface anisotropy coordinates), separating collinear and non-collinear states, is determined.

The Fe–Pt-rich alloys has recently attracted a lot of interest for their potential development of the hard magnetic L10 (also denoted γ1) FePt phase with high magnetocrystalline anisotropy. An alloy with the nominal composition Fe65Pt25Nb2B8 has been synthesised by rapid quenching of the melt. The phase evolution in the as-cast ribbons was monitored by energy dispersive X-ray diffraction of the synchrotron radiation. It is shown that the Fe65Pt25Nb2B8

Intermetallic Fe–Pt–Nb–B alloys with 3 different compositions have been synthesized by rapid solidification technique and their phase structure was characterized by means of X-ray diffraction and Mössbauer spectrometry. It is shown that Fe68Pt21Nb2B9 and Fe65Pt25Nb2B8 as-cast samples consist mainly of A1 soft magnetic f.c.c. Fe–Pt phase, while the Fe68Pt13Nb2B17 as-cast sample exhibits topological short-range order, typical for amorphous