[en] The authors presents some experimental results of amorphous alloy Fe₃₉Ni₃₉Mo₄Si₁₂B₆ after fast neutron (14 MeV) irradiation with neutron fluence of 10¹⁴ n/cm² by means of differential scanning calorimetry (DSC) and Moessbauer spectroscopy (MS). Furthermore, the influence of neutron irradiation on microstructure is discussed

[en] Antiferromagnetic CoO nanoparticles ranging from 10 to 80 nm were prepared by the sol-gel process. The morphology, size and structure of the particle were characterized by TEM microscopy, electron diffraction and X-ray diffraction. Magnetic properties were measured using VSM and MPMS magnetometers. The nanoparticles has an FCC structure with a lattice parameter of 4.258 A. Anomalous magnetic properties, such as hysteresis, were observed in CoO nanoparticles comparing to the course grain materials. The coercive force increases as the particle size is reduced, but decreases when the size is less than 20 nm. The magnetization increases below 100 K for the nanoparticles. However, no significant shifts of Neel temperature were observed. This magnetic behavior could be interpreted in terms of a core-shell model, in combination with the magnetic interaction between particles

[en] Ultrafine Fe-B amorphous alloy powders were prepared by reducing Fe²⁺ ions using KBH₄ and NaBH₄ in aqueous solution. Adjusting technological factors, the amorphous powders around the composition of Fe₆₅B₃₅ can be easily obtained, but in the vicinity of eutectic point (Fe₈₀B₂₀) a certain amount of α-Fe often appears in the samples. From the Moessbauer spectrum, the crystallization products of the Fe₆₃B₃₇ amorphous powder are α-Fe and Fe₂B phases. The measurement of ¹¹B spin echo nuclear magnetic resonance (NMR) at 8 K showed that Fe₂B-like and Fe₃B-like short range orders (SRO) exist in the amorphous powder of Fe₇₆B₂₄. (orig.)

[en] Based on the three-dimensional micromagnetic simulations, we present a method to tailor the microwave permeabilities of magnonic metamaterials cells by a designed nanoring structure. The results show that the permeabilities and resonant frequency are depended on the wall's thickness of nanorings. The underlying mechanism is ascribed to the presence of strong demagnetization fields, which are associated to the ring's wall. In addition, the products of magnetic susceptibility and resonant frequency are larger than that predicted from Snoek's law in polycrystalline particles. These results are direct manifestations of the bi-anisotropy model.

[en] Fe(x)/Mo(y) multilayered thin films (MLF) with y=7.0 nm and x=0.7, 1.3, 2.6, 3.6, 13.0 nm were fabricated by radio frequency (RF) sputtering. X-ray diffraction evidences that these films have a good periodicity and bcc structure for both Fe and Mo layers. Moessbauer spectra at room temperature (RT) are used to investigate the structure and the local magnetic properties of the interfaces between Fe and Mo layers. It is found that the interfaces present alloying features, i.e. the Fe atoms are randomly substituted by Mo atoms. Magnetic anisotropy which forces magnetic moments to lie in the film plane and reduced magnetic moments in interface region were observed. The specific magnetization of the films exhibits a BT^3/2 dependence with very large values of B which can be attributed to the distribution of exchange interaction in the interfaces. (orig.)

[en] Epitaxial Fe films are grown on Si(0 0 1) and Si(1 1 1) substrates by molecular beam epitaxy at room temperature. Several samples of one Fe/Si structure are subjected to rapid thermal annealing from 100 to 500 °C. The annealing impact on the morphological, magnetic properties and interfacial heterostructures of these samples is examined by atomic force microscopy, vibrating sample magnetometer and transmission electron microscopy, respectively. The results demonstrate that the material system Fe/Si grown at room temperature exhibits an abrupt interface and is thermally stable up to a temperature of 150 °C.

[en] Nanowires of metal, alloy, compound, and ferrite have been electrodeposited in anodic aluminium oxide templates. The structure and magnetic properties of the nanowires are characterized by ⁵⁷Fe Moessbauer spectroscopy combining with other techniques. It is found that the metal and alloy nanowires have a very strong magnetic anisotropy. The surface distribution of the magnetic moment is different from that of the interior. The Debye temperature of Prussian blue nanowires derived from hyperfine interaction parameters is lower than that of the bulk. The properties of the ferrite nanowires are strongly related to the structure of nanowires.

[en] The short range order (SRO) of amorphous Fe₈₀B_20-xC_x (x=0, 2, 4, 7, 9) alloys has been investigated by means of Moessbauer effect (ME) and nuclear magnetic resonance (NMR). Both the amorphous samples and the samples annealed at lower temperatures (693-713 K) for a short time (10 minutes) were used. The Moessbauer measurement shows that the experimental spectra of annealed samples consist of the subspectra of α-Fe and bct-Fe₃B for x=0, while of α-Fe, bct-Fe₃B and o-Fe₃(B, C) for x=2, 4, 7, 9. Moreover, the relative intensities of the subspectra originating from o-Fe₃(B, C) increases with carbon concentration. These results are consistent with those of NMR very well. (orig.)

[en] Co_100-xZr_x (40 nm) thin films with different Zr compositions were grown on silicon substrates by radio frequency magnetron sputtering. The coercivity decreased with an increase in the Zr composition. A uniaxial anisotropy existed in the Co_100-xZr_x films, and the anisotropy field of the films decreased from 55 to 40 Oe with the increase of Zr composition. The resonance frequency and linewidth were decreased with the increase of the Zr composition during the permeability measurements. For samples with x=0 and 9, the magnetic anisotropy effective field and saturated field were obtained by fitting the external magnetic field dependent resonance frequency with Landau-Lifschitz-Gilbert equation. Therefore, it is an effective way to get the adjustable anisotropy field and linewidth, which is desirable for obtaining the high resonance and high permeability ferromagnetic film materials for high frequency application.

[en] Highly ordered Prussian blue nanowires with diameter of about 50 nm and length up to 4 μm have been fabricated by an electrodepositing technology with two-step anodizing anodic aluminum oxide films. The Moessbauer spectra taken between 15 and 300 K indicate that the hyperfine parameters decrease as the temperature increases. The temperature dependence of the quadrupole splitting, the isomer shift and the spectra area are discussed. A decrease of Debye temperature for Prussian blue nanowires was found with respect to that of Prussian blue bulk.