The magnetic properties of a ferromagnetic cylinder containing an antiphase boundary with antiferromagnetic interactions are studied using atomic Monte Carlo simulation. The approach to saturation shows a reduced magnetization compared with the completely ferromagnetic sample, even in huge applied fields. The magnetization profiles are studied as a function of the number of ferromagnetic planes in the cylinder with 80 atoms per plane and also as

The magnetic behavior of nanocrystalline alloys has been modeled using atomic Monte Carlo simulation. The model consists of a cubic lattice composed of a ferromagnetic nanograin in a ferromagnetic matrix. The magnetizations of nanograin core, surface and interface regions and matrix were studied as a function of the exchange coupling between the nanograin and the matrix, as well as of the nanograin/matrix volume ratio, equivalent to the crystalline

The effect of surface anisotropy on the magnetic ground state of a ferromagnetic nanoparticle is investigated using atomic Monte Carlo simulation for spheres of radius R=6a and R=15a, where a is the interatomic spacing. It is found that the competition between surface and bulk magnetocrystalline anisotropy imposes a "throttled" spin structure where the spins of outer shells tend to orient normal to the surface while the core spins remain parallel

After a presentation of structural aspects of iron-based nanocrystalline alloys, the magnetic behaviours of those two-phase magnetic structures are conceptually discussed at high temperatures as a function of the crystalline volumetric fraction, on the basis of the magnetic correlation length compared to the distances between crystalline grains. In addition, some results predicted by an approach based on Monte-Carlo simulation are then briefly presented:

The crystallization behaviour of amorphous melt-spun SmxFe80-xB20 ribbons is investigated by differential scanning calorimetry, X-ray diffraction and Mossbauer spectrometry. On increasing the Sm content. the crystallization temperature reaches a maximum for a critical Sm content (x(c) approximate to 8) and the main crystallization products are different below and above x,. This is attributed to a change in the short-range local order in the amorphous

The crystallization of amorphous SmxFe80-xB20 melt spun ribbons is studied over an extended range of composition (0 < x < 8). Differential scanning calorimetry scans reveal different endo- and exothermic effects depending upon the composition. X-ray diffraction and Mossbauer studies for samples annealed at temperatures close to the onset of the first exothermic effect prove that, during the primary crystallization of the amorphous ribbons, both alpha-Fe

Applied field Mossbauer spectrometry is used to investigate the magnetic structure in two amorphous Sm-Fe-B ribbons with measured compositions Sm7.2Fe72.8B20 and Sm12Fe68B20. The applied field dependence of the hyperfine field agrees with the ferromagnetic coupling between the Fe and Sm magnetic moments. For the Sm7.2Fe72.8B20 ribbon, the magnetic moments are aligned in the applied field direction for fields higher than 4 T. For the Sm12Fe68B20 ribbon,

Mossbauer spectrometry and magnetic measurements are employed to experimentally investigate the magnetic behavior of nanocrystalline Fe73.5Cu1Nb3Si13.5B9 ribbons obtained by appropriate annealing of the amorphous precursor. A detailed analysis of the correlation between the microstructure of annealed samples and their magnetic properties is provided. Thermomagnetic data allow the Curie temperatures of both amorphous residual matrix and nanocrystalline

The nanocrystallization of two soft magnetic amorphous Finemet-type ribbons of the nominal composition Fe73.5Cu1Nb3Si13.5B9 and Fe73.5Cu1Gd1Nb2Si13.5B9 synthesized by a melt spinning technique is reported. The crystallization process was monitored by differential scanning calorimetry (DSC) that allows identification of the primary crystallization temperature as well as the other exothermic events occurring during crystallization process. The resulting

Magnetic behavior of the isolated ferromagnetic bimetallic nanoparticles is investigated in relation with the competition between exchange interaction and surface and bulk anisotropies. Experimental results on AgCo bimetallic nanoparticles are presented and correlated with Monte Carlo simulation of low temperature spin ordering. The nature of spin disorder at the surface, responsible for the reduction of the overall saturation magnetization is briefly