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Au/Co/SmCo/Au films with different SmCo and Co thickness were grown on silicon (100) substrates by electron-beam evaporation. The morphology of these films has been analyzed by transmission electron microscopy. The magnetic properties of the bilayers were investigated by magneto-optical Kerr effect. Hysteresis loops show a SmCo/Co single-phase behavior indicating a strong exchange coupling between the soft and hard phases. Also, we have shown that the magnetization reversal dynamics is dominated by domain wall motion.

In this paper, we report on self-assembled Co nanoparticles deposited in and on porous silicon (PS) matrix by using UHV evaporation. Four samples were prepared by varying the Co deposited thickness (t = 3, 5, 7 and 10 nm). All samples have been investigated by means of Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Physical Properties Measurement System (PPMS). The increase of t has induced an increase of the nanoparticle diameter from 3 nm to about 150 nm. Referring to the magnetic characterizations, this increase has been followed by a single to multi-domain transition. Therefore, this has been evidenced by a switching from superparamagnetism to purely ferromagnetism accompanied by a change in the magnetic reversal dynamics. Thus, by performing micromagnetic calculation, we have shown that a transition from the uniform rotation to vortex state occurs at a critical diameter of about 55 nm.

Cobalt ferrites nanoparticles Co x Fe 3-x O 4 (1≤ x B ) range from 294 to 240 K. Kneller's law fitting of the coercive field dependence on the temperature exhibits a non-neglected interparticle interaction and a wide size distribution according to the difference found between T B and the Kneller transition temperature T BK .

In this study, SmCo-based films with different thicknesses were grown on a Kapton substrate by ultra-high vacuum (UHV) evaporation process. Two effects on magnetic properties of SmCo films have been investigated: the effect of the variation of the magnetic layer thickness and the effect of the substrate temperature. The morphology and the structure were explored by atomic force microscopy and X-ray diffraction. It has been shown that the film morphology and its crystallographic orientation changed significantly with increasing thickness. Magnetic measurements reveal a strong correlation between magnetic and structural properties. The highest magnetic squareness ratio M r/ M s (0.8) and a maximum coercive field at room temperature, of about 2 kOe, are obtained when the SmCo layer thickness is 15 nm.

A small quantity of cobalt nanograins deposited on the surface of WO 3 sensors produces an important change in the WO 3 conductance. Indeed, the cobalt changes the conduction type of the sensors from n to p-type. An increase in conductance of the WO 3 sensors under ozone is thus observed. This behaviour was investigated for two added quantities of deposited cobalt (15 A and 30 A). The modified sensors were tested under ozone before and after an annealing process under dry air at a temperature of 673 K for 1.5 h. The obtained response shape and mechanisms to ozone were explained by chemical reactions related to oxidation of the cobalt incorporated which can probably occur during the annealing process.

During an anodization process, porous silicon (PS) consisting of pores with a diameter of about 40 nm and a depth from 5 µm to 40 µm has been produced. To achieve oriented channels in this mesoporous range, a p+-type Si wafer was electrochemically etched in an aqueous electrolyte of HF. We report the formation, after the anodization step, of a cobalt nanostructure in a porous silicon matrix. Co nanocrystals on and in a porous silicon layer have been prepared by the UHV evaporation technique and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). This technique was performed to show the chemical element distribution within the channels. It is found that the deposition condition is an important factor for obtaining nano-structures. Initial deposition leads to Co particle penetration in silicon pores whereas subsequent deposition results only in an increase of the thickness at the surface with no further penetration. Additional experiments were carried out by using the magneto-optical Kerr effect to obtain information about the magnetic properties. The first results show that the magnetic response for layers