Investigation of magnetic properties in 57 Fe/Al multilayers (original) (raw)
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Journal of Applied Physics, 2008
Fe/Al multilayer thin films with an overall atomic concentration ratio of Fe: Al=1:2 have been prepared by ion-beam sputtering. Phase formation and microstructural evolution with thermal annealing have been studied by x-ray reflectivity, cross-sectional transmission electron microscopy, dc magnetization, and conversion electron Mössbauer spectroscopy. These studies show that although the starting composition is Al rich, the intermixing of Fe and Al at the interfaces leads to the formation of a magnetic Fe 3 Al-like region at the interface. Thus, the magnetic contribution in the as-deposited multilayer structure ͑MLS͒ is not only from pure Fe but also from an Fe 3 Al-like region formed at the interface. On annealing the MLS, a stable nonmagnetic MLS consisting of intermetallic B2 Fe 50 Al 50 separated by thin Al layers is formed. Further annealing only induces better ordering of Fe 50 Al 50 and does not destroy the MLS.
Magnetic and structural properties of Fe/Al multilayers
Journal of Magnetism and Magnetic Materials, 2002
Static and dynamic magnetic properties of Fe/Al multilayers, grown by RF magnetron sputtering on Si(1 0 0), are investigated. Magneto-Optical Kerr Effect shows in-plane uniaxial anisotropy and very soft behavior on six samples characterized by different number of bilayers. The coercive fields range between 2 and 8 Oe. Brillouin light scattering reveals spin-wave surface modes that depend on the number of Fe/Al repetitions and are attributed to the total multilayer stack and to individual layers. r
Investigation of Fe/Al multilayers
Journal of Magnetism and Magnetic Materials, 2002
The effect of number of layers in Fe(25 (A)/Al(25 (A) multilayer samples is studied using ferromagnetic resonance (FMR) and magnetization measurements. It is observed that more than four bilayers of Fe/Al give rise to two to three resonances, out of which one is a common/main one and occurs at about 900 Oe. Using the main resonance, effective magnetization M eff has been deduced from FMR and is found to be about 1 2 of the value of saturated magnetization, M s ; of bulk iron. Magnetization measurements also give similar reduced value of magnetization M but a little larger value. Temperature dependence of M; i.e., MðTÞ shows a peak in zero-field-cooled samples, while no such peak is observed in field-cooled MðTÞ: MðTÞ can be fitted to T 3=2 dependence in RTF100 K region whether M is derived from FMR or magnetization measurements. FMR and magnetization measurements indicate antiferromagnetic interlayer coupling between iron films may be coexisting with the ferromagnetic interaction within each iron film.
Journal of Applied …, 2008
Fe/Al multilayer thin films with an overall atomic concentration ratio of Fe: Al=1:2 have been prepared by ion-beam sputtering. Phase formation and microstructural evolution with thermal annealing have been studied by x-ray reflectivity, cross-sectional transmission electron microscopy, dc magnetization, and conversion electron Mössbauer spectroscopy. These studies show that although the starting composition is Al rich, the intermixing of Fe and Al at the interfaces leads to the formation of a magnetic Fe 3 Al-like region at the interface. Thus, the magnetic contribution in the as-deposited multilayer structure ͑MLS͒ is not only from pure Fe but also from an Fe 3 Al-like region formed at the interface. On annealing the MLS, a stable nonmagnetic MLS consisting of intermetallic B2 Fe 50 Al 50 separated by thin Al layers is formed. Further annealing only induces better ordering of Fe 50 Al 50 and does not destroy the MLS.
Journal of Physics and Chemistry of Solids, 2018
Keywords: Fe 2 CrAl intermetallic phase Thin film Mössbauer spectroscopy Soft magnetic properties A B S T R A C T The structural and magnetic properties of disordered Fe 2 CrAl intermetallic thin film obtained from thermal annealing of [Al 17 Å / 57 Fe 25 Å /Cr 13 Å ] x20 multilayer have been studied. The combination of X-ray reflectivity, X-ray diffraction, DC magnetization, and conversion electron Mössbauer spectroscopy are used to characterize the as-deposited and annealed multilayers. The structural and conversion electron Mössbauer spectroscopy studies show that on annealing [Al 17 Å / 57 Fe 25 Å /Cr 13 Å ] x20 , multilayer at 773 K, a thin film of Fe 2 CrAl phase is obtained. DC magnetization studies show the formation of an excellent soft magnetic material with coercivity in the range of 2-22 Oe and saturation magnetization of ∼500-900 emu/cm 3. The Curie temperature is found to be much higher than that of its bulk. Disordered Fe 2 CrAl phase formed after annealing at 833 K for 3 h is highly stable and totally reversible against high temperatures. We believe that this composition in thin film form, with an excellent soft magnetic properties is a suitable material for many multi-functional applications.
Mössbauer and SEM study of Fe–Al film
Hyperfine Interactions, 2006
Fe–Al alloy with Fe/Al ratio of 3:1 was first prepared by argon arc melting. It was subsequently coated on glass slide and cellophane tape using an electron beam gun system to have a thickness of 2,000 Å. X-ray diffraction spectrum of the coated sample indicates a definite texture for the film with a preferential growth along the Fe(110) plane. SEM micrographs of the film showed the presence of nano islands of nearly 3 × 1012/m2 surface density. Composition of different parts of the film was determined using EDAX. Room temperature Fe-57 Mössbauer spectrum of coated sample showed the presence a quadrupole doublet with a splitting of 0.46 mm/s, which is typical of Al-rich iron compounds. MOKE study shows an in-plane magnetic moment.
Effect of Al overlayers on the magnetic properties of Fe thin films
In this work, we report on the e!ect of Al overlayers on the magnetic properties of Fe thin "lms. In-plane ferromagnetic resonance has been used to measure the resonance "eld and linewidth, as a function of the azimuthal angle, H, and Al layer thickness, t . The data are interpreted in the framework of a model that includes cubic magnetocrystalline and out-of-plane uniaxial anisotropies, and dispersions of the cubic axes. The main e!ect of the Al overlayer is to enhance the cubic magnetocrystalline anisotropy of the Fe "lm and to reduce the out-of-plane uniaxial anisotropy. The Al layer also induces angular dispersion in the cubic axes. We found no clear evidence of a 1/ t dependence of the sample parameters, as expected for interface e!ects.
Study of interface structure of Fe/Al multilayers
Journal of Applied Physics, 1996
Structural and magnetic ordering of the interfaces determines the physical properties of multilayered structures. Interfaces of Fe/Al multilayers were studied using Mössbauer effect spectroscopy. The samples were fabricated by dc planar magnetron sputtering at room temperature on polyester substrates. The observed spectra indicate that the interfaces have a common structural composition and for thin Fe layers, the whole Fe layer forms mixed phases at the interface. For larger Fe layer thickness, the interface is formed using an about 12-Å-thick Fe layer. Besides the hyperfine field component of bcc Fe, six different magnetic components were identified in all samples ͑with larger Fe layer thickness͒. The intensities of the components were determined from the area under the absorption peaks of the Mössbauer spectra of the corresponding phases. The average canting angle of the Fe magnetic moments, as obtained from the spectra, indicate parallel magnetic anisotropy for all phases.
Structural evolution of Fe-Al multilayer thin films for different annealing temperatures
Journal of Physics Condensed Matter, 2001
The phase formation during thermal annealing of Fe/Al multilayer thin films prepared by electron-beam evaporation, with an overall atomic concentration ratio of Fe:Al = 1:1, has been studied by Rutherford backscattering spectrometry (RBS), x-ray diffraction spectroscopy (XRD), and conversion-electron Mössbauer spectroscopy (CEMS). At the annealing temperature of 473 K some degree of atomic mixing between Fe and Al layers is revealed only by CEMS. At 573 K a large degree of atomic mixing is indicated also by RBS, leading to the nucleation and growth of the B2 FeAl intermetallic phase, as detected by means of XRD and CEMS. At 673 K all Fe atoms have reacted and the multilayer film is transformed into a defective B2 phase. Annealing at higher temperature increases the structural order of the B2 phase. We suggest that the observed phase formation occurs in three stages: (1) formation of a thin intermixed layer between Fe and Al in the as-deposited sample; (2) Al migration into the initial intermixed layer; (3) B2 phase growth at the interface between the intermixed layer and the Fe layer.
Parametric Characterizations of Sputtered Fe/Al Multilayer Thin Films
This study contains parametric characterizations of four different series of Fe/Al multilayer thin films sputtered under thicknesses of Al layers (7.5, 35 and 95 nm), deposition rates (0.02 and 0.06 nm/s), Fe layer thicknesses (7.5, 12.5 and 27.5 nm) and total thicknesses (100, 125 and 175 nm), separately. The X-ray diffraction measurements showed that all films have a mixture of face-centered cubic (fcc) and body-centered cubic (bcc) phase. The face-centered cubic (fcc) and mostly body-centered cubic (bcc) phase turned to the mostly fcc and bcc phase as the thickness of Al layer increased. On the other hand, the intensity of peaks belongs to bcc structure increased and mostly bcc structure was detected when the deposition rate increased. The roughness on the surfaces of Fe/Al multilayer increased as Al layer thickness decreased and deposition rate of layers increased. Saturation magnetization value changed coherently with the film content for all films. Coercivity, H c value was significantly affected by different surface morphologies, and granular surface caused higher H c values for Fe/Al multilayer thin films. It was found that crystalline structure, surface properties and magnetic properties of Fe/Al multilayer thin films depend strongly on the deposition parameters.