Smooth single-crystal α-Mn2O3 nanowires have been fabricated using a one-step solid-state reaction method. X-ray diffraction patterns show that the nanowires have pure phase of α-Mn2O3. Transmission electron microscopy was employed to investigate the size and morphology of the products. The α-Mn2O3 nanowires exhibit mean diameter of 50nm and length of 10μm. Selected-area electron diffraction pattern demonstrates the single-crystal structure of the α-Mn2O3 nanowires, which are in good agreement with the X-ray diffraction results. The processes of the reactions and the phase transitions were also studied by using a simultaneous thermal gravimetric/differential thermal analyzer. It is found that the concentration of the precursor MnCO3 is a crucial factor in the formation of the nanowires. This work provides the probability of the industrialization of fabricating smooth single-crystal α-Mn2O3 nanowires.

Ni-Co-P-coated SiO2 particles were prepared using electroless plating method. The morphology, crystal structure, surface compositions, magnetic and microwave absorption properties of the composite powder were investigated by scanning electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, vibrating sample magnetometer and vector network analyzer, respectively. It was found that the silica powder was successfully coated with Ni-Co-P alloy. The ultrafine Ni-Co-P-SiO2 powder-paraffin wax composite possesses excellent microwave absorption properties. The maximum microwave loss reaches 48.6 dB at 4.2 GHz with a thickness of 3.10 mm. The intrinsic reasons for microwave absorption were also investigated

Dynamic magnetic susceptibilities of high-aspect-ratio permalloylike nanorings outer diameter 20nm, inner diameter 12nm, length L range 12-500nm are studied using three-dimensional micromagnetic simulations. The investigated systems show two major resonance modes associated with volume and shape resonance modes, corresponding to low and high resonance frequencies, respectively. When L is below 40nm, only the shape resonance mode is seen with a frequency predicted using the Kittel's equation and demagnetization factor calculated for a ring. At sufficiently large L, the frequency of the volume mode converges to that of the Kittel prediction. For other lengths, however, neither the low resonance frequency nor the high resonance frequency agrees with the Kittel's equation. A weighted average resonance frequency fa i that contains two major modes is introduced and shows the same trend as the results predicted by the Kittel's equation for all lengths. The frequencies of volume and shape resonance modes have also been investigated by changing the exchange stiffness constant A and the saturation magnetization Ms.

The dynamic susceptibilities of permalloylike nanowires 20 500 20 nm3 have been investigated using the three-dimensional object oriented micromagnetic framework OOMMF code. The investigated systems show two resonant peaks associated with a "bulk" and an "edge" mode, which are attributed to the local effective field relevant to the local magnetic moments. A local analysis for ferromagnetic resonance calculation has been developed. It handles the local magnetic moments at the edge and the middle of the nanowire, respectively. The resonant frequencies of the edge mode are directly proportional to Ms or A under the same fundamental length scale, i.e., the exchange length.

Fe29Co71 and Fe19Bi81 antidot arrays, with different ajmensions, are prepared with the rf magntron supttering method onto the porous alumina substrate. The size and shape of antidot arrays are characterized by scanning electron microscopy. The glancing angle x-ray diffreaction patterns of Fe29Ci71 and Fe19Ni81 antidot arrays indicate the bcc and fcc structures, respectively. The coercivities of both the alloys show abnormal thickness dependence, whick are discussed qualitatively by considering the pinning and the thickness effect to the films.