Oe For Films Research Articles

Characterization of Erbium Substituted Yttrium Iron Garnet Films Prepared by Sol-Gel Method

Yttrium iron garnet (YIG) thin films substituted erbium ions (Er+3) Er0.4Y2.6Fe5O12 films were prepared by a sol-gel method at different temperatures which varied from 800 to 1000°C for 2 hours in air. Magnetic and microstructural properties of the films were characterized with X-ray diffraction (XRD), the field emission scanning electron microscopy (FESEM), and vibrating sample magnetometer (VSM). The XRD patterns of the sample have only peaks of the garnet structure. The lattice constants decrease, while the particle size increases from 51 to 85 nm as the annealing temperature increases with average in thickness of 300 nm. The saturation magnetization and the coercivity of the samples increased from 26 (emu/cc) and 28 Oe for the film annealed at 800°C to 76 (emu/cc) and 45 Oe for film annealed at 1000°C, respectively.

Soft Magnetic Properties of Co-Fe-Al-O Thin Films with High Bs

The structure and properties of Co0.7Fe0.3-Al-O films, prepared by rf magnetron sputtering using oxygen and argon gases, were studied. Soft magnetic properties were found in the films when the compositional ratio of Al-O corresponded to Al2O3. The (Al-O) concentration has a significant influence on the structure and properties of soft magnetic Co0.7Fe0.3-Al-O films. With increasing (Al-O) concentration, the structure of the film changes from micro-crystalline to granular. The coercivity decreases to less than 5 Oe in films containing only a few percent of (Al-O). The magnetostriction also decreases with increasing (Al-O) content, and is almost zero around 27% (Al-O), where the saturation magnetization is near 12 kG. On the other hand, the electrical resistivity and anisotropy field of the films increase with increasing (Al-O) content. By selecting the (Al-O) content in Co0.7Fe0.3-Al-O films, it is possible to find films that have suitable properties for a variety of high-frequency magnetic devices.

Giant magneto-impedance in Co-rich amorphous wires and films

A comprehensive analysis of magneto impedance (MI) phenomena in Co-rich amorphous materials is presented on the basis of skin effect in combination with dynamical magnetization processes. We consider a MI effect for which the domain walls are perpendicular to the current and field direction. Thus, the magnetization induced by current proceeds, via both the wall movement and moment rotation. The magnetic responses of impedance in wires and films have some common features and can be understood from the same mechanism. The sensitivity of the magnetic response in a small sample (1 mm length and a few micrometer thickness) is about 10%/Oe in wires and 5%/Oe in films. The model describes well the existing experimental data for moderate frequencies, There is some quantitative discrepancy for the case of a very strong skin effect, where the position dependence of basic magnetostatic parameters is important. >

Effects of CoCrPt layer thickness on the magnetic and structural properties of CoCrPt/Cr thin films

The effects of CoCrPt layer thickness on the magnetic and structural properties of CoCrPt/Cr thin films have been investigated. The in-plane coercivity increased with decreasing thickness for most of the examined compositions, and reached 3050 Oe for films with 13 at.% Pt. It was also found that a decrease of the CoCrPt film thickness leading to M/sub r//spl delta/ >

PROPERTIES OF MBE-GROWN SUPERLATTICES AND ULTRA-THIN FILMS

We have used Molecular Beam Epitaxy (MBE) to grow single-crystal Co/Pd superlattices and Co/TM (TM=Cu, Pd, Ag) bilayers and sandwiches along the three high-symmetry crystal directions; [001], [110], and [111]. In the case of Co/Pd superlattices, we previously reported from x-ray diffraction measurements that for small Co thicknesses the (001) oriented superlattices are coherently strained in-plane to near the bulk Pd lattice spacing. This strain leads to a very large in-plane magnetoelastic volume anisotropy for these superlattices. Here we report quantitative in situ RHEED measurements of Co deposited on Pd (001) that confirm this coherently strained growth. We have also used in situ polar Kerr ellipticity measurements to study the perpendicular magnetic behavior of Pd/Co/TM (111) sandwich structures, where TM is the non-magnetic transition metal overlayer Ag, Cu or Pd. We observed perpendicular loops with coercive fields of H c ≤ 200 Oe for the uncovered Co films for t co ≤ 6 Å, becoming in-plane above this thickness. However, subsequent deposition of just one atomic layer (≈ 2 Å) of any of the TM over the Co resulted in strongly perpendicular, square hysteresis curves with H c ≥ 900 Oe for all films in the Co thickness range studied.

Absorption résonnante ferromagnétique pour les couches minces électrolytiques de Ni-Fe-Mo avec anisotropie biaxiale

Magnetic absorption resonance is studied in electrodeposited thin films of permalloy (80% Ni) and permalloy with Mo (5% Mo) having biaxial anisotropy achieved by ferromagnetic coupling. The film thickness was 5300 Å. The anisotropy field has values which decrease from 9.6 to 9 Oe for films without Mo and from 5.8 to 3.1 Oe for films with 5% Mo when the working frequency increases from 3 to 9 MHz. The angle between the axes is 20° in both cases. The effective damping parameter corresponding to the precession of the magnetic moment around an equilibrium direction of the constant field perpendicular to the anisotropy axis, decreases with the increase of r.f. field from 3 to 9 MHz as follows: from 0.35 to 0.10 for the films without Mo and from 0.65 to 0.32 for the films with Mo, the angle between the axes being of 20° in both cases. For the precession of the magnetic moment around a direction perpendicular to the second axis, the effective damping parameter decreases from 0.27 to 0.10 for films without Mo and from 0.66 to 0.28 for films with Mo for the same angles between axes and over the above frequency range.

Sur la dispersion de l'anisotropie et de la stabilité dans le temps des couches électrolytiques de Ni-Fe-Mo avec anisotropie biaxiale

The angular and amplitude dispersions of the anisotropy in Ni-Fe-Mo films with biaxial anisotropy have been studied. The permalloy films had a thickness of 5000 Å and those of permalloy with 5% Mo a thickness of 5400 å. The films were deposited onto plane copper substrates. The angular and amplitude dispersions, measured by the resonance absorption method, decrease with an increase in the angle between the anisotropy axes, having values of 4° and 2.8 Oe, respectively, for the permalloy films with an angle of 5° between the axes, and 2° 30′ and 2 Oe for films with an angle of 22° between the axes. For the permalloy films with Mo the dispersions decrease from 7° 30′ and 3.2 Oe to 6° 30′ and 2.9 Oe for an increase of the angle between the anisotropy axes from 10° to 20°. The time variation (over 1000 h) of the angle between the anisotropy axes is given. Decreases from 22° to 17° and from 10° to 7° respectively for permalloy and permalloy with 5% Mo are obtained.