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This paper studies the effects of a high magnetic field on the structural evolution and magnetic properties of nanocrystalline films prepared on quartz substrates by a molecular beam vapor deposition (MBVD) method. Atomic force microscope, X-ray diffractometer, transmission electron microscope and vibrating sample magnetometer were used to study the microstructures and magnetic properties of the films. The results indicate that high magnetic field has no obvious influence on crystal structures except changing the lattice constant of the films. However, the high magnetic field can refine particle size. The film deposited under magnetic field tends to grow through columnar mode because of the magnetized particles aligning along the direction of magnetic field. Furthermore, the ordered and dense arrangement of atoms results in more spins contained in per unit volume and improves the saturation magnetization (Ms). Ms of the 6 T film increases by 70% (578 emu/cm3) than that of the film without magnetic field (341 emu/cm3), and the coercivity is also slightly increased for the 6 T film. Nanocrystalline magnetic Ni films were prepared under high magnetic field. It is found that a high magnetic field changes the growth mode and increases the saturation magnetization of Ni film. The high magnetic field also improves the ordered and dense arrangement of Ni atoms. [ABSTRACT FROM AUTHOR]

The kinetics of the reactive diffusion at the liquid Al/solid Cu interface was investigated at T = 973 K, 1023 K, and 1073 K in a high magnetic field of 11.5 T. During the annealing process, three stable compounds (δ, ξ2, and η2) layers were formed at the interface of the couples, and a power function relationship between the mean thickness of the diffusion layers and the annealing time kept stable. Without magnetic field, the exponent of the power function for each compound layer was higher than 0.5, but it was close to or even smaller than 0.5 with a magnetic field. Compared with the field-free environment, the migration of the liquid/solid interface due to interdiffusion decreased in the presence of a magnetic field. A considerable decrease in the effective diffusion coefficient under a magnetic field provided a likely explanation for the experimental results. [ABSTRACT FROM AUTHOR]

In this study we have explored how a high magnetic field (HMF) affects the structure and magnetic properties of Fe thin films fabricated on Si (100) substrates at various substrate temperatures by using a thermal evaporation method. At a substrate temperature of room temperature (RT), the HMF increased the width of column and the formation energy of the films. This behavior occurred because the HMF induced an excess energy-Zeeman energy which is larger than the sum of the kinetic energy and thermal energy of Fe without the HMF. This increased the particle size and decreased the roughness of the film deposited at RT and 6 T. When the substrate temperature was increased to 400 °C, the growth mode is changed from columnar (RT) to layered (400 °C). The HMF increased the grain size. The film deposited at RT and 6 T had much improved soft magnetic properties from its modified microstructure. While thermal disturbances decreased the effect of HMF on the magnetic properties of the film deposited at 400 °C. In particular, the influence of HMF on the microstructure and magnetic properties of Fe films is significant not in the evaporation stage but in the condensation process of film. [ABSTRACT FROM AUTHOR]

The influence of interdiffusion on the magnetic properties of Co/Si (100) films after thermal annealing in the presence of a strong magnetic field was investigated. The interdiffusion coefficients of films that were annealed at temperatures of 380 °C and 420 °C in the presence of high magnetic fields were not affected. However, the interdiffusion coefficient of films annealed at 400 °C in the presence of a high magnetic field decreased significantly. The change in the interdiffusion coefficient, caused by high magnetic field annealing, increased the content of the magnetic phase. This increase in the magnetic phase improved the saturation magnetization. A new method of high magnetic field annealing is presented that can modulate the diffusion and magnetic properties of thin films. [ABSTRACT FROM AUTHOR]

The Fe 60 Ni 40 (in atomic %) nanoparticles (NPs) thin films with 90 nm thickness were prepared on 25 and 400 °C quartz substrates by using the molecular beam vapor deposition (MBVD) method under a 6 T high magnetic field (HMF). The effects of a HMF on the structure evolution and properties of Fe–Ni thin films were studied by using X-ray diffraction, atomic force microscopy, transmission electron microscopy, vibrating sample magnetometer and four-point probe method. The results show that the crystallinity of thin films is enhanced by a 6 T HMF, and a 6 T HMF changes phase composition of thin films on 25 °C substrate. It is found that the nanoparticle size decreases; the nanoparticle size distribution becomes narrow, and the root mean square (rms) roughness of thin films decreases under a 6 T HMF relative to that without HMF. These lead to the decrease of coercive force, and the increase of in-plane remanence ratio under a 6 T HMF. [ABSTRACT FROM AUTHOR]

Abstract: Isothermal heat treatment experiments of an Al–4.8mass%Cu alloy were carried out under different magnetic field intensities, at different temperatures and for different holding times. The influence of high magnetic fields on area fraction of θ phase in the solidified microstructure was investigated. It was found that the area fraction of the θ phase was lower when imposing the magnetic field compared to samples heat-treated without magnetic field. In other words, the magnetic field accelerated the phase transformation to the equilibrium state. In addition, the area fraction of the θ phase was independent of magnetic field intensity. This effect of high magnetic fields on the decreasing of the θ phase was discussed from the viewpoint of the effect of high magnetic fields on diffusion. [Copyright &y& Elsevier]

Abstract: Nanocrystalline Fe x Ni1−x (in at%, x=0.74, 0.6, 0.55, and 0.3) thin films were prepared on a 25°C quartz substrate by using a molecular beam vapor deposition method with and without a 6T magnetic field. The microstructure of the thin films was characterized by energy dispersive x-ray spectroscopy, x-ray diffractometry and transmission electron microscopy. The magnetic and electrical properties of the thin films were examined by a vibrating sample magnetometer and four-point probe method. Results show that the thicknesses of these films with different compositions are 50, 90, 80, and 150nm, correspondingly. The crystallinity of Fe x Ni1−x (x=0.74 and 0.6) thin films is enhanced, and the γ 〈111〉 orientation degree of the Fe x Ni1−x (x=0.55 and 0.3) thin films increases under a 6T magnetic field. The grain refinement and defect decrease under 6T magnetic field are affirmed by TEM. A 6T magnetic field can help the thin films transform from anisotropy to isotropy. The soft magnetic properties of the Fe x Ni1−x (x=0.74, 0.6, 0.55, and 0.3) thin films are enhanced, and their resistivities decrease under a 6T magnetic field. [Copyright &y& Elsevier]

Abstract: The magnetic properties of Fe–49%Sn monotectic alloys were investigated after the alloys were solidified with and without a high magnetic field of 10T. The results showed that there was a significant difference between their hysteresis loops measured parallel and perpendicular to the applied high magnetic fields for the solidification process. Therefore, high magnetic fields applied in solidification process increased the magnetic anisotropy in the alloys. Along the parallel directions of the high magnetic field applied in their solidification process, the saturation magnetization M s, magnetic susceptibility dM/dH M and remanent magnetization of Fe–49%Sn monotectic alloys were increased obviously, which resulted from the improvement in the aligned microstructure of Fe–Sn alloys by applying the high magnetic field to the solidification process. A modified Stoner–Wohlfarth model was introduced to explain the experimental results. [Copyright &y& Elsevier]

Abstract: The effects of high magnetic field annealing on the interdiffusion of Co/Ni bilayer films were investigated in this paper. A clear CoNi alloying zone can be observed by field emission scanning electron microscopy and energy dispersive spectroscopy, for samples annealed with and without magnetic field. Significant Co and Ni interdiffusion was verified by X-ray photoelectron spectroscopy. Based on the thickness of the diffusion layer, the distribution of atoms and the microstructure of interfacial products, the interdiffusion coefficients of the bilayer diffusion couples were calculated. Compared with the no-field case, the interdiffusion coefficient clearly increased when a high magnetic field of 12T was applied. This effect can be attributed to an increase in the chemical potential gradient induced by magnetic free energy in a high magnetic field. [Copyright &y& Elsevier]

Abstract: The application of a high magnetic field during pack aluminization process induced a significant change in the final products at the surface of substrate Cu. Experimental studies demonstrated that the coatings consisted of two layers namely α + γ 2 and α with the magnetic flux density (B) ranging from 0 to 8.8 T, whereas only α layer with Kirkendall voids was observed in case of B ≥10 T. With B increasing, the total thickness of coating first increased to a maximum at a field of 6.6 T, and then decreased with further increasing magnetic flux density. These results may be attributed to the contradictory effects of high magnetic fields on chemical reaction and on diffusion. [Copyright &y& Elsevier]