D.S. Xue

Tunable cut-off frequency by in-plane uniaxial anisotropy in (Fe66.9Co33.1)86.8Sm13.2 films

(Fe66.9Co33.1)86.8Sm13.2 (FeCoSm) thin films with thickness from 110 to 330?nm are fabricated on silicon (1?1?1) substrates by magnetron co-sputtering under ambient condition. The as-deposited FeCoSm thin film is amorphous when the thickness is less than 150?nm. When the thickness increases further, the film becomes partially crystallized. The maximum in-plane uniaxial anisotropy field is up to 1200?Oe. After the films are heat treated in vacuum with a magnetic field, the in-plane uniaxial anisotropy field decreases with an increase in annealing temperature and becomes zero after annealing at 500??C. The dynamic magnetic properties of the FeCoSm films are also investigated in the range 0.1?9?GHz. Based on the one-terminal micro-strip transmission-line perturbation method and an analysis by the Landau?Lifshitz equation, the anisotropy field and the resonance frequency of the FeCoSm_films are in the range 50?1200?Oe and 1.8?12.1?GHz, respectively. The anisotropy field and resonance frequency of the film can be controlled by varying the film thickness or annealing temperature, this means that FeCoSm films have great potential in high-frequency applications.

X-ray diffraction and Mössbauer studies of γ'-(Fe1-xSnx)4N compounds (0.0≤x≤0.3)

Abstract The structure and magnetic properties of γ′-(Fe 1− x Sn x ) 4 N samples have been studied using X-ray diffraction and 57 Fe Mossbauer spectroscopy. It has been shown that the single-phase (Fe 1− x Sn x ) 4 N compounds can be prepared in the composition range of 0.0⩽ x ⩽0.3, which have the similar structure as γ′-Fe 4 N The lattice parameter with the increase of Sn concentration can be well fitted with two linear relationships a 0 ( x )=3.795+0.019 x (with x ⩽0.10 ) and a 0 ( x )=3.797+0.228( x −0.10) (with 0.1⩽ x ⩽ 0.3). The fitting results of Mossbauer spectra indicate that the hyperfine parameters have the same changing tendency with lattice parameter, and the Sn atoms have a preference to be located at the corner site.

Tunable in-plane uniaxial anisotropy and the magnetization reversal mechanism of patterned high-frequency soft magnetic FeTa strips

FeTa films with thickness of 110 nm are fabricated on glass substrates by magnetron sputtering, and then a series of strips is designed on the FeTa films by conventional optical lithography and the ion beam etching method. Patterned FeTa strips show a tunable in-plane uniaxial magnetic anisotropy property in contrast with the magnetic isotropic property of as-deposited FeTa thin films. The magnetization reversal mechanism of the patterned FeTa strips is investigated via the in-plane angular dependences of magnetization and coercivity. The angular dependence of coercivity (ADC) is explained well in terms of the two-phase model, giving good quantitative agreement with the experimentally measured M-shaped ADC curve. The domain structure and spatial resolution magneto-optical Kerr effect measurement indicate that the smaller the strip width, the stronger will be the anisotropy field. Regarding the dynamic magnetic properties, a transformation from Debye dispersion spectrum for strips with weak anisotropy to natural resonance spectrum for strips with strong anisotropy is finally obtained. The tunable in-plane anisotropy fields of the FeTa strips result in tunable high-frequency soft magnetic properties by altering the strip width, indicating that patterned FeTa strips have great potential in high-frequency soft magnetic application fields.

Influence of a small addition of Nd on Mössbauer spectra of amorphous FeB alloys

Abstract Mossbauer spectroscopy was used to investigate the influence of Nd-substitution on the hyperfine field distribution and isomer shift of amorphous FeB alloys. It is observed that a small addition of Nd causes the decrease of average hyperfine field and isomer shift and an increase of the width (ΔH) of the hyperfine field distribution P(H). At low temperature the average hyperfine field of amorphous Nd 4 Fe 77.5 B 18.5 alloy shows a temperature dependence of H a (T) = H a (0)(1 − BT 3/2 ) with a larger value of B than that of amorphous Fe 81.5 B 18.5 alloys.

Mössbauer study of amorphous Nd x Fe81B19-x (0≦x≦19) alloys

Amorphous NdxFe81B19-x (0≤x≤19) alloys have been studied by57Fe Mössbauer spectroscopy. It is found that the average and peak hyperfine fields and the isomer shift decrease with increasing Nd content x. The magnetization for the samples containing Nd shows a strong tendency to lie in the direction perpendicular to the ribbon plane and its direction varies with Nd content.