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Room-temperature photoluminescence has been achieved from rare-earth-doped amorphous (a‐) GeN films. The samples were prepared by the radio-frequency-sputtering method, and light emission from the rare-earth (RE) centers was obtained after irradiating the films with a highly focused laser beam. As a result of this laser annealing procedure, almost circular holes with approximately 1‐μm diameter were produced on the surface of the a‐GeN films. The area nearby these holes correspond to crystalline Ge and coincide with the regions, where relatively strong RE-related luminescence takes place. These laser-annealed areas can be easily and conveniently managed in order to generate different microscopic luminescent patterns. Depending on the RE ion employed, visible and near-infrared light emission were obtained from the patterns so produced. The development of these micrometer-sized luminescent centers, as well as their probable mechanisms of excitation-recombination, will be presented and discussed. The importa...

The possibilities for fabricating solid solutions of (Ba1−x,Srx)TiO3 (x≤0.5,1.0) by crystallization of amorphous films and for improving their dielectric properties by adjusting the Sr content were investigated. Thin amorphous films were prepared from powder targets consisting of mixtures of BaTiO3 and SrTiO3 by sputtering with a neutralized Ar‐ion beam. The amorphous films crystallized into (Ba1−x, Srx)TiO3 solid solutions with a cubic perovskite‐type structure after annealing in air at 923 K for more than 1 h. The Debye‐type dielectric relaxation was observed for the amorphous films, whereas the crystallized films showed paraelectric behavior. The relative dielectric constants were of the order of 20 for the amorphous samples, but increased greatly after crystallization to about 60–200, depending on the composition; a larger increase in the dielectric constant was observed in the higher Sr content films, in the range x≤0.5, which could be correlated with an increase in the grain size of the crystallites. The crystallization processes responsible for the difference in the grain size are discussed based on the microstructural observations.

Different anisotropy components originating from various mechanisms in dc‐magnetron sputtered Tb39Fe70 films have been identified. The inverse magnetostrictive anisotropy component was determined by comparing the anisotropy of Tb30Fe70 films when they were removed from their substrates and when they were still attached to their substrates. The single‐ion anisotropy component was then derived by subtracting the pair‐ordering anisotropy, which was determined as the anisotropy of Gd21Fe79 films which had been removed from their substrates, from the anisotropy of Tb30Fe70 films which had been removed from their substrates. By this method, single‐ion and inverse magnetostrictive anisotropies were found to contribute 30–60% and 30–65%, depending on argon sputtering pressure, of the total anisotropy, respectively. Pair‐ordering was responsible for less than 10% of the total anisotropy in dc‐magnetron sputtered Tb30Fe70 films. Thermal stability of each anisotropy component was studied by annealing films when still attached to their substrates. The anisotropies of films, which had been annealed and removed from their substrates were then compared with those of films, which had also been removed from their substrates but without annealing. Effects of Ar sputtering pressure on the thermal stability of anisotropy were also investigated. Better thermal stability was found in single‐ion and pair‐ordering anisotropy than in magnetostrictive anisotropy. Films deposited at lower argon pressures show better thermal stability of single‐ion and pair‐ordering anisotropy than those deposited at higher argon sputtering pressures.

Strain sensitivity of amorphous (Fe90Co10)78Si12B10 sputtered film was studied in detail, so as to examine the potential of film for highly sensitive microstrain gauges. The film exhibited the figure of merit F=(Δμ/μ)/e (change in film permeability μ per unit strain e) of 1.2×105, the value of which is comparable to that of amorphous ribbons. Reflecting the large value of F, the high-frequency impedance of the film was also subjected to change due to strain: the change in impedance of 46% was observed at 100 MHz applying a strain of 300×10−6. It is also demonstrated that utilizing the strain-dependent impedance, a small strain of 0.2×10−6 can be detected with the film.

The magnetic force microscope (MFM) was used to study the displacement of domain walls (DW) in amorphous TbFe alloy films and Co/Pd multilayer films with high spatial resolution. The reversible bending of domain wall segments pinned to defects and irreversible, jumplike displacement of domain wall segments were imaged with the MFM in an applied magnetic field. The maximum reversible displacement of domain walls was 50–100 nm and the length of the segments which reversibly curved in the field was about 150 nm. Measurement of the change in radius of curvature of a DW segment in response to an applied field allowed estimation of the DW energy density and self-demagnetizing field of the film acting on the DW. The DW energy density for the TbFe films was about 1 erg/cm2. It was shown that the self-demagnetizing field acting on a domain wall depends on the domain structure surrounding the studied DW segment. For instance, for a film with saturation magnetization 100 G and thickness 80 nm, which exhibited a maze...

We report on magnetoresistance measurements in SmCo5 amorphous films with a giant imprinted magnetic anisotropy. At low applied field parallel to the easy axis, the magnetoresistance exhibits a hysteretic, square, and antisymmetric shape. The antisymmetry in the magnetoresistance is a result of the non-uniform distribution of the magnetization direction over the sample in conjunction with the extraordinary Hall effect. Moreover, the combination of anisotropic magnetoresistance measurements and magnetic domain imaging demonstrates that the symmetry depends on the magnetization orientation with respect to the applied field.

This report is on magnetic properties of samples of 0.5 Fe2O3‐(0.5−x)Bi2O3‐xLi2O (x=0.1–0.4) prepared in oxygen atmospheres by rf sputtering techniques. The films develop a spontaneous moment M only when annealed in air at temperatures Ta≥675 K. The room‐temperature M vs Ta data show a maximum in M for Ta=775–875 K even though x‐ray diffraction data do not show the precipitation of any crystalline ferromagnetic or ferrimagnetic phases. The spontaneous moment could be attributed to the presence of ordered clusters in the amorphous film. The magnetization is found to be dependent on the concentration of nonmagnetic Li2O: M increases with increase in x. An in‐plane anisotropy in the films is evident from ferromagnetic resonance studies (FMR) at x‐band frequencies. The anisotropy field increases with increasing x. The room‐temperature in‐plane FMR linewidth decreases with increasing x.

A new type of high‐resistive soft magnetic amorphous film possessing superior properties such as high resistivity (ρ), high‐saturation induction (Bs), and high permeability (μ) in the high‐frequency range prepared by cosputtering Co0.40Fe0.40B0.20‐SiO2 was obtained. These films which have Bs higher than 8 kG in the range less than ∼55% of Si‐O volume fraction, consist of a two‐phase structure of amorphous magnetic metal particles (∼50 A) scattered in the amorphous nonmagnetic Si‐O region. ρ increases exponentially with the increase of Si‐O volume, with diminishing eddy current loss in the very high‐frequency range. Some of these films (Bs∼12 kG, Hc∼0.3 Oe, ρ∼500 μΩ cm), in fact, have a superior permeability compared with sputtered sendust films and regular amorphous films used as high‐density recording head cores in the high‐frequency range over 10 MHz.

Amorphous alloy thin films of (Co95Zr5)100−xDyx with a well‐defined in‐plane uniaxial anisotropy Ku were prepared by rf sputtering. The saturation magnetization, Ku, and the coercive field were studied as a function of temperature and for the composition range 4≤x≤20. Ms could be fitted by the molecular‐field model, Ku interpreted by a single‐ion anisotropy process, and Hc by a model of Alben, Becker, and Chi [J. Appl. Phys. 49, 1653 (1978)]. At low temperatures (T≤50 K) and for the whole concentration range a new type of aftereffect is observed, the main characteristic of which is described.

We have studied the magnetic behavior of amorphous Y‐3d based systems, using resistivity and Hall effect measurements. YxNi1−x metallic glasses show a very different magnetic behavior from Fe glasses, with a cross over (x=0.22) from weak itinerant ferromagnetism to paramagnetism. Two more magnetic metallic glasses have been studied, a typical ferromagnetic system Fe‐Si‐Y (with Fe content only 52%) and a noncollinear ferrimagnetic (sperimagnetic) system (Fe‐Si‐Tb). In spite of their very different magnetic mechanisms the resistivities all show low temperature minima with logarithmic dependence below the minima temperatures. This behavior is not magnetic field dependent, with applied fields up to 70 kOe. We show Hall effect measurements that easily distinguish the different intrinsic mechanisms.We have studied the magnetic behavior of amorphous Y‐3d based systems, using resistivity and Hall effect measurements. YxNi1−x metallic glasses show a very different magnetic behavior from Fe glasses, with a cross over (x=0.22) from weak itinerant ferromagnetism to paramagnetism. Two more magnetic metallic glasses have been studied, a typical ferromagnetic system Fe‐Si‐Y (with Fe content only 52%) and a noncollinear ferrimagnetic (sperimagnetic) system (Fe‐Si‐Tb). In spite of their very different magnetic mechanisms the resistivities all show low temperature minima with logarithmic dependence below the minima temperatures. This behavior is not magnetic field dependent, with applied fields up to 70 kOe. We show Hall effect measurements that easily distinguish the different intrinsic mechanisms.

Amorphous Tb/Co compositionally modulated films were deposited on Si substrates with different modulation layer thicknesses ranging from about 2.5 to 15 A. The nominal Tb to Co layer thickness ratios were systematically varied and the complex refractive index (n and k) and polar magneto‐optical Kerr effects (rotation and ellipticity) were measured in the 3000–8000‐A spectral range as well. The samples were divided into two groups. In one group, the thickness of the Co layers was fixed, the Tb layer thickness varied. In the second group, the thickness of the Tb layer was fixed, and that of the Co layer thickness varied. The Kerr rotation and the coercivities of the samples showed very consistent and interesting changes. X‐ray diffraction and x‐ray fluorescence were also performed on the samples, which revealed layered structures, or compositional modulation, and provided information on the Tb to Co atomic ratios in the samples.

Because the light rare‐earth element Nd makes a significant contribution to the Kerr effect and the heavy rare‐earth element Dy can improve the coercivity and perpendicular anisotropy, NdDyFeCoTi magneto‐optical material was studied. The alloy targets were prepared by a vacuumm melting method with compositions (NdxDy1−x)25(Fe0.65Co0.30Ti0.05)75 with x=0.2–0.3. Because of the addition of Ti, the mechanical strength of the target was improved. Amorphous NdDyFeCoTi films were prepared by rf magnetron sputtering onto glass substrates at zero bias, a low Ar pressure of 3–7 mTorr, and a low‐input sputtering power of 100–300 W. The magnetic and magneto‐optical properties of these films were studied by VSM, Kerr hysteresis tracer, and Auger electron spectroscopy. The Kerr angle θk of 0.3° and the coercive force Hc of 3–5 kOe have been found. The stability of the films was examined by exposure in air for one month and annealing at 100–250 °C. The magneto‐optical properties of the films exhibit no obvious change af...

Photosensitivity of thermally evaporated chalcogenide amorphous films of xGe45Se55-(1−x)As45Se55 (x = 0, 0.25, 0.5, 0.75, 1) composition is investigated when exposed to the laser light of 660 nm wavelength. The photo-induced effects transition from photodarkening (PD) to photobleaching (PB) as Ge45Se55 x increases from 0 to 1. The degree of PB correlates with the concentration of Ge–Ge homopolar bonds. The kinetics of PD and PB can be well described by a stretched exponential function. The dynamic response of PB is much faster than that of PD films in the present glass system.

The work reports the effect of a tensile stress on the magnetic domain of FeCoSiB amorphous films. The domain structures of the unstressed and stressed FeCoSiB amorphous films with different tensile strains have been studied by magnetic force microscopy (MFM). With the increase of the tensile stress in the samples, it has been observed that the domain structures transform from irregular domains into parallel strip domains, and magnetic contrasts decrease. The MFM image disappears when the tensile stress is strong enough. A model has been presented to explain the evolution of the domain structures under the tensile stress. The effects of the stress on the domain of the films have been discussed.

We report magnetic properties of Y3Fe5O12 (YIG) films on thermally oxidized Si (100) and (Gd3Ga5O12) GGG (111) substrates. Amorphous YIG films with the cation ratio Y:Fe=3.04:4.96, deposited by rf-magnetron sputtering at room temperature in pure argon atmosphere, were crystallized by postannealing (600–900 °C) of amorphous films in air and in 500 ppm oxygen. While postannealed YIG films on GGG substrates were well textured, those on Si (100) were randomly oriented. High-quality YIG films could be better obtained in the reduced (500 ppm O2) oxygen atmosphere than air since more effective YIG growth during annealing process and lower FMR linewidth (ΔH) of films could be achieved.

Amorphous chalcogenide thin film deposition can be achieved by a spin-coating technique from proper solutions of the corresponding glass. Films produced in this way exhibit certain grain texture, which is presumably related to the cluster size in solution. This paper deals with the search of such a correlation between grain size of surface morphology of as-deposited spin-coated As33S67 chalcogenide thin films and cluster size of the glass in butylamine solutions. Optical absorption spectroscopy and dynamic light scattering were employed to study optical properties and cluster size distributions in the solutions at various glass concentrations. Atomic force microscopy is used to study the surface morphology of the surface of as-deposited and thermally stabilized spin-coated films. Dynamic light scattering revealed a concentration dependence of cluster size in solution. Spectral-dependence dynamic light scattering studies showed an interesting athermal photo-aggregation effect in the liquid state., 15 pages, 8 figures

Thin film heads made of Co‐based amorphous films with high saturation magnetization were reported to have superior capabilities for high‐density magnetic recording.1 However, it was found that the uniaxial anisotropy is changed during head fabrication processes. In this study, we investigate the relaxation process of the uniaxial anisotropy of sputtered Co‐Zr amorphous films. 1‐μm‐thick Co‐Zr films of 1.4 T were prepared by rf sputtering. Uniaxial anisotropy was induced by the magnetic field of 50 Oe during deposition. After deposition, annealing was performed in the dc field of 500 Oe applied parallel to the easy axis of the films for stabilizing the uniaxial anisotropy (preannealing). The preannealing temperature was changed from 200 to 350 °C. The films were annealed again in a field along the hard axis to reduce the uniaxial anisotropy. Decrease of the anisotropy field was discussed based on Richter‐type relaxation,2 where τ2 is the maximum and τ1 is the minimum relaxation time, respectively. Without ...

The feasibility of direct overwrite utilizing a demagnetization field was successfully demonstrated by employing transition‐metal‐rich side Tb‐Fe‐Co‐Cr amorphous films, which is different from previously reported rare‐earth‐rich side films.1,2 For this purpose, 3.5‐in. magneto‐optical discs were made in the form SiN/TbFeCoCr/SiN on a pregrooved polycarbonate substrate. To evaluate the capability of direct overwrite, we chose the writing and erasure conditions in such a way that erasure laser power (PE) was set higher than the writing power (PW), applying a constant weak external field (Hex) directed in the direction of erasure. Thermomagnetic writing and erasure at 1.76 MHz were carried out on a disk rotating at 1800 rpm. The carrier‐to‐noise ratio, C/N, thus obtained was 26 dB in the conditions of PW=8 mW and Hex=−100 Oe. This signal was completely erased by the dc erase procedure (PE=10 mW and Hex=−100 Oe). Furthermore, this signal value was repeatedly obtained by the above writing and erasure sequence....

In searching for a possible dependence of magnetic surface anisotropy on film thickness, the magnetic surface anisotropy constant Ks of compositionally modulated amorphous Fe70B30‐Ag films1 was measured by means of a method2 involving the dependence of the ferromagnetic resonance (FMR) fields on the magnetic layer thickness 2L. The ratio of the Ag to the Fe70B30 thickness was 3 to 1 while 2L ranged from 1.6 to 90 A. Measurements were made with the applied static magnetic field parallel and perpendicular to the plane of the sample, at both X‐ and K‐band frequencies for at least 14 values of 2L in each case. The results of magnetization measurements, made by SQUID magnetometry, have already been reported.1 Using the measured values of the thin‐film magnetization and the aforementioned method, the value of Ks has been determined over the entire range of 2L. The results are consistent with a constant value of Ks for 2L>16.5 A, while Ks is found to decrease monotonically as 2L is reduced from 16.5 to 1.6 A. A ...

Characteristics of Tb‐Fe‐Co amorphous films have been systematically investigated in order to optimize compositions suitable for magneto‐optical recording medium with high readout signal. In order to optimize alloy composition, Curie temperature TC and compensation temperature Tcomp are summarized as functions of both Tb and Co contents. Crystallization temperature Tx of Tb‐Fe‐Co amorphous films has been also measured to be about 400 °C and tends to increase with replacing Fe by either Co or Tb. To evaluate Tb‐Fe‐Co films as a magneto‐optical recording medium, carrier C and modulation noise Nmod (defined by the difference in noise before and after writing) are measured as a function of external field Hex. It is found that written bits of large Nmod show an irregular shape, while those of small Nmod are of regular one. To reduce Nmod and obtain high readout C/N, films with lower saturation magnetization Ms (that is, low demagnetization field) at just below writing temperature are preferred.

Magnetic anisotropy has been determined for evaporated amorphous films of Gdx(Fe1−yCoy)1−x with 0.08

Magnetic anisotropy dispersion in sputter‐deposited rare‐earth transition‐metal amorphous films is measured by the methods of Hall hysteresis loops and torque magnetometry. The inhomogeneity in the orientation of the easy axes of magnetization is found to be rather large; the mean inclination angle of the axes from film normal is 16.5° in a Gd–Tb–Fe film. Results show a clear correspondence between the anisotropy dispersion and Kerr rotation angle, and both depend on the bias voltage applied to the substrates during sputtering. Anisotropy dispersion is an important property for evaluating the amorphous magnetic films for magneto‐optical storage application.

Oxygen diffusion behavior in indium‐alloyed TbFe films is studied under several aging conditions. The oxygen‐suppression mechanism is discussed. The oxygen‐diffusion coefficients of TbFeIn films after aging are 1.5×10−22 m2/s at 80 °C and 2×10−24 m2/s at room temperature, both at 85% relative humidity. These coefficients are one‐tenth those previously reported for aged GdTbFe and TbFeCo films. The activation energy of TbFeIn films is 1.5 times larger than that of GdTbFe films. A diffusion model based on In characteristics and involving vacancy sites in the films is presented.

A new type of ferromagnetic amorphous alloy with a two‐phase structure was found in cosputtered Fe‐B‐N films. The microstructure was identified to be composed of two amorphous phases with about 50 A or less in size; one is a ferromagnetic amorphous phase of Fe‐B‐N alloy and the other is a nonmagnetic and high resistive amorphous phase of boron nitride. The homogeneous mixture of these two phases in the films resulted in unique features for magnetic and electrical properties. In comparison to sputtered Fe‐B films, the Fe‐B‐N films exhibit higher saturation magnetizations and the electrical resistivity is about 3–103 times higher. The compositional dependence of Curie and crystallization temperatures also differs from those of the sputtered amorphous Fe‐B films. Furthermore, the corrosion resistance of the films is improved in the presence of nitrogen.

Static, transient, and ac signal characteristics of semiconducting glasses are investigated in terms of electrothermal instabilities. The simple analytical treatment assuming adiabatic conditions is evaluated by comparing its approximate results with the exact computed results. Electrothermal instability could account for the device static characteristics and delay time. However, the conduction mechanism should change during the switching process to account for switching times of the order of 10−9 sec. The possibility of stable dynamic characteristics is discussed.

A new type of high‐resistivity soft magnetic amorphous alloy film with a very fine two‐phase heterostructure was found in cosputtered Fe‐B‐C films. These amorphous films are found to have a number of superior properties in the high‐frequency range (over∼10 MHz) over not only regular amorphous films, but also sendust film cores, which have already been applied to high‐density recording media having high coercivity. They were found to exhibit unique isotropic soft magnetic B‐H curves with high Bs (∼15 000 G), low Hc (∼0.3 Oe), and high ρ (∼400 μΩ cm), and the reduced magnetization versus reduced temperature curve was almost the same as the j=∞ curve of the Brillouin function. A very high permeability with less core loss, especially in the high‐frequency range, was also experimentally observed in those amorphous films.

The mechanism of magnetostriction in rare‐earth–transition‐metal amorphous films was investigated based on a single ion anisotropy model for rare‐earth atoms using a point charge approximation. The theory was compared with the observed magnetostriction in (Gd0.75R0.25)19Co81 films with various rare‐earth elements R. The dependence of the observed magnetostriction on substitutional rare‐earth elements R is well explained with this model. Screening of an electric field was found to be essential for magnetostriction, and a screening function was determined from the observed magnetostriction. The screening was found to be of the type in which an electric field decreases more rapidly with an increase of distance than a Coulombic interaction.

The influence of the introduction of oxygen gas and nitrogen gas into the chamber during deposition on the perpendicular magnetic anisotropy of Gd‐Co amorphous films deposited by ion beam sputtering has been investigated. The films deposited without O2 and N2 addition show perpendicular magnetization in the vicinity of compensation composition. However, the perpendicular anisotropy of them is much smaller than that of the films deposited by rf sputtering. When sputtering ion energy, deposition rate, and Ar pressure are 0.5∼3 keV, 19∼30 A/min, and 8×10−3∼8×10−2 Pa, respectively, the films obtained have almost the same perpendicular anisotropy. On the other hand, the incorporation of oxygen in the films leads to a remarkable increase of perpendicular anisotropy. The films deposited at O2 pressure of 1.6×10−3 Pa have an effective perpendicular anisotropy constant K⊥(K⊥ = Ku‐2πMs2) of about 5×105 erg/cm3, where Ku is 1.1×106 erg/cm3. On the contrary, the incorporation of nitrogen decreases the perpendicular a...

Magnetic anisotropy in sputter‐deposited SmxCo100−x amorphous films depended on the substrate temperature even for a narrow composition range of 18≤x≤26. Deposition between 90 and 140 °C brought a negative perpendicular anisotropy. All the films were magnetically isotropic in the film plane with zero torque curve for a field rotated in the film plane, suggesting that the negative perpendicular anisotropy did not come from easy axes of uniaxial anisotropy due to some structures being in the film plane. A large negative anisotropy vanished after annealing. On the other hand, a positive anisotropy which overcomes the demagnetizing energy was induced by a deposition at 60–90 °C. Films with a positive perpendicular anisotropy had a relatively large electric resistivity and hence a large Hall resistivity. The magnetostriction measurement showed that a stress (film/substrate)‐induced anisotropy did not play an important role in both positive and negative perpendicular anisotropies. A possible origin of the large...

Postdeposition annealing of some sputtered rare‐earth–cobalt (YCo3, GdCo, and HoCo) amorphous films in an atmosphere of rare gases Ne, Ar, Kr, and Xe has been shown to induce a strong in‐plane anisotropy Ku?−5×105 erg/cm3. Also, after the rare‐gas anneal, the coercive force and the resonance linewidth are remarkably reduced and one observes in YCo3 films a well‐defined spin‐wave spectra which obeys well the quadratic‐dispersion law. The presence of in‐plane anisotropy in the annealed films is tentatively attributed to the formation of Co‐Co pairs along the thickness.

A thin film head using CoZr amorphous films has been developed for high density magnetic recording. The head has a single‐layered 17‐turn spiral copper coil, 0.2‐μm head gap length, 15‐μm track width, and 2‐μm‐thick CoZr films on an IBM 3370 type slider. The copper coil was electroplated through a photoresist pattern, which was fabricated by the oxygen ion milling to obtain a high aspect ratio (1.5 μm width, 3.4 μm thickness, 3.5 μm space). CoZr films used here have excellent magnetic properties, such as low coercive force (Hc≤0.05 Oe), high permeability ( μ≂3500 at 10 MHz), and high saturation magnetization (4πMs ≂14 000 G). These heads were evaluated using 8‐in. Co‐Ni‐P plated disks which have a 300‐A‐thick magnetic layer (Hc=600 Oe, Br =7200 G) and a 200‐A‐thick protective layer. D50=36 KFRPI and overwrite=−34 dB (24 KFRPI on 8 KFRPI) were obtained at 19.7 m/sec relative velocity and 0.25 μm head‐disk spacing. These values were superior to those for heads using Permalloy films (D50=25 KFRPI, overwrite=...

The magnetic properties of amorphous bias‐sputtered films of Gdx(FeyCo1−y)1−x are investigated. In particular, the effects of changing the relative amounts of Co and Fe are studied. Increasing the iron by 12% lowers the exchange between the rare earth and the transition metal by about 35%. There is no apparent change in the anisotropy constant with iron‐cobalt ratio.

The influence of the addition of hydrogen H2 on the penpendicular magnetic anisotropy of the Gd–Co films deposited by ion beam sputtering has been investigated precisely. Specimen film about 5000 A thick were deposited on glass slide and rock salt substrates under the strict control of hydrogen partial pressure. The incorporation of H2 into Gd–Co films, as that of O2 and N2, leads to shift of compensation composition at room temperature from the Gd content of 18 at. % to higher Gd content. The Gd–Co:H films show perpendicular magnetization within very wide region of the composition, from about 55 at. % Co to 75 at. %. Besides, the incorporation of H2 increases the K⊥ of the films with Co content less than 75 at. %; however, it decreases that of the films with Co content more than 75 at. %. The electron diffraction pattern of the films changes from broad ring to two separated rings with the incorporation of H2, which indicates that the incorporation of hydrogen causes a phase separation of gadolinium hydri...

The dependence of structural and magneto‐optical (MO) properties of TbFeCo films on Ar pressure, deposition rate, and magnetic field have been investigated by using the facing‐target sputtering (FTS) system. The films prepared at high deposition rate and/or with the plasma‐free substrate did not have any appreciable columnar structure. The Kerr rotation angle of the films was as high as 0.37°. No significant change in the magneto‐optical properties of the films was observed after exposing them to air for 250 days. MO disks fabricated by the FTS system had a high C/N ratio of 57 dB at a bit length of 5 μm.

Experiments on the extraordinary Hall effect in sputtered amorphous rare‐earth–cobalt films show that the effect is due to the cobalt magnetization rather than that of the rare earth.

Sputtered Co94−xZr6Mox (4.4≤x≤17 at. %) films have been investigated as a soft‐adjacent‐layer (SAL) material for trilayered magnetoresistive (MR) sensors with a MR element layer, a current shunt layer, and a SAL for biasing layer. The saturation magnetization 4πMs linearly decreases from 14 to 3 kG with an increase in Mo content. The magnetic anisotropy field Hk decreases to a low value, equivalent to that for NiFe MR films, as the Mo content is increased. The magnetoresistance ratio Δρ/ρ is negative, but sufficiently small, namely one‐hundredth of that for NiFe films, while the electrical resistivity ρ, about 140 μΩ cm, is 5.6 times greater than that for NiFe films. The films also have a small magnetostriction coefficient λs on the order of 10−7. A 500‐A‐thick CoZrMo film with 12 at. % Mo content is selected as the SAL, because a lesser thickness causes an extreme increase in Hk. Higher Mo content degrades the temperature characteristics of the magnetic properties, due to the lower Curie temperature. Tri...

Magnetic properties of Fe1−xBx sputtered films were investigated in the range 0.09

By making use of the high permeability and the excellent high‐frequency characteristics of Co‐metal amorphous multilayered films, an inductor was fabricated. In order to improve the high‐frequency characteristics, stripe patterned films were studied. The inductor consists of two of these films and a ferrite yoke. The value of inductance and quality factor were measured in the frequency range of 0.01–200 MHz. Although the value of the present inductance is small compared with other small size inductors developed so far, excellent high‐frequency characteristics may be expected if an inductor is fabricated composed solely of these multilayered films.

Saturation magnetizations and magnetic anisotropy constants were determined for a series of amorphous GdCo films prepared by thermal evaporation. The films covered the composition range from Gd0.05Co0.95 to Gd0.40Co0.60 and were studied by means of ferromagnetic resonance and a force balance magnetometer. The films, in contrast to those prepared by sputtering, had a hard perpendicular direction of magnetization when Co was less than 91 at.%, and easy and moderate directions within the plane of the film. The anisotropy constant can be expressed in terms of sublattice magnetizations by Ku=0.660MCo2 +2.218MCoMGd+0.097MGd2. The results are explained based on a pair‐ordering mechanism. The composition and temperature dependence of saturation magnetization is essentially the same in evaporated and sputtered films.

Direct measurements were made by means of SQUID magnetometry of the magnetization of ultrathin Fe50B50 and Fe70B30 amorphous films at room temperature. The film thicknesses used included most of those investigated in the authors’ recent ferromagnetic resonance (FMR) determinations of the surface anisotropy Ks and the magnetization M of such films. The directly measured values of M confirm adequately the M values obtained by computer fitting of a theory to experimental FMR data. Thus, the present experiments offer substantial support for the reliability of the FMR method for measurements of Ks and M in ultrathin films.

The effect of Au addition on the magnetic properties and thermal stability of amorphous CoyZr1−y alloys produced by sputtering is described. Change of the saturation magnetization, the saturation magnetostriction, and the crystallization temperatures were measured for Au additions up to 2.0 at. %. For y=87.2 little appreciable effect was observed, but for y=93.2 and 94.2 rapid decrease of the magnetostriction was observed for small amounts of Au additions. Thermal stability of magnetic softness is also improved appreciably.

Rare‐earth transition metal amorphous thin films which have uniaxial magnetic anisotropy perpendicular to the film plane were prepared by rf‐sputtering or thermal evaporation. It was found that these amorphous magnetic films have a large extraordinary Hall effect. We measured the surface potential distribution for various domain patterns in the films. The correlation between the surface potential distribution and the shape of domain pattern was observed. We also measured the relation between the Hall voltage and the position of straight domain wall. From this measurement, we confirmed that the geometry of the element (the ratio of the length L to the width W) affects the positional dependence of Hall voltage, and the sensitive region in the film with respect to the Hall electrodes. We measured the domain wall velocity in Gd‐Co amorphous films. Indicial response of the straight domain wall in these films to the pulse magnetic field was obtained.

Amorphous oxide films with a composition of Bi2DyFe5O12 have been prepared by rf sputtering technique. The crystallization process was investigated using x‐ray diffraction, differential thermal analysis, magnetic properties, magnetic resonance spectra, magneto‐optical Faraday spectra, Raman spectra, and infrared reflection spectra. Amorphous oxide films exhibit very small magnetization and Faraday rotation at room temperature. At about 600 °C amorphous films crystallize to a garnet phase. With crystallization the magnetization and Faraday rotation increase rapidly. Raman and infrared spectra studies show the presence of tetrahedral sites in the amorphous films. As the annealing temperature increases, the peaks corresponding to octahedral and dodecahedral sites occur successively. It is of interest to note that amorphous oxide films containing Fe3+ ions show no magnetic resonance spectra at 71 and 300 K. The films annealed above crystallization temperature show a normal resonance spectrum. With increasing ...

The deposition of polycrystalline silicon films by the low‐temperature crystallization of as‐deposited, mixed‐phase silicon films obtained by low‐pressure chemical‐vapor deposition was studied. It was found that this type of material, consisting of crystalline regions embedded in an amorphous matrix, can crystallize in threefold to fourfold shorter crystallization time than that required for the complete crystallization of as‐deposited amorphous films. The faster crystallization was attributed to the combination of the growth of the preexisting crystallites and the faster nucleation and growth of random crystallites in mixed‐phase films. In addition, it was shown that by utilizing composite films, consisting of an amorphous layer and a mixed‐phase layer, a comparable grain size to that of crystallized amorphous films can be obtained. The key process parameters, controlling the grain size and the crystallization time of composite films, were found to be the layer sequence, the deposition rates of the layer...

Structure dependence of electrical properties was investigated for amorphous and epitaxial thin films of chloroaluminumphthalocyanine vacuum deposited on both glass and KCl. The extrinsic conductivity in the dark was improved by elevating substrate temperatures, depending on the morphological change from granular, discontinuous films deposited at a substrate temperature of 25 °C to uniform, continuous ones at 250 °C. The photocurrents under monochromatic light illumination increased in proportion to the amount of adsorbed O2 in the amorphous films on glass. A regular doping form of O2 in the epitaxial film on KCl could enhance photocarrier generation. The granular, discontinuous morphology in the films caused a frequent charge‐carrier recombination at the grain boundaries and defect sites. In the intrinsic region the amorphous films exhibited a higher dark conductivity due to the π‐electron interaction between the randomly arranged molecules and gave a moderate activation energy for conduction. The epitaxial film with a regular orientation exhibited a significantly higher activation energy for intrinsic dark conduction because of a weak molecular interaction between the standing molecular columns.

Magneto‐optical recording materials with high remanent Kerr rotation at a short wavelength were successfully obtained in a trilayer form. NdCo amorphous films with an in‐plane magnetization were sandwiched between TbFeCo amorphous films with strong perpendicular anisotropy and high coercivity. The thickness of the top layer of the TbFeCo film facing an incident laser beam is less than the light‐penetration depth. Triple‐layered films [Tb18Fe49Co33 (5 nm thickness)/Nd18Co82(10 nm)/Tb18Fe49Co33(200 nm)] thus obtained show a remanent Kerr rotation angle θKr = 0.37°–0.46° at wavelength λ=400–850 nm, coercivity Hc = 2 kOe, and good square loop (Mr/Ms = 1). The figure of merit √RθK, where R is reflectivity, is 0.24–0.31 at λ=400–850 nm, which is higher than that of conventional TbFeCo amorphous films (√RθK = 0.12–0.27 at λ=400–850 nm).

We have performed rapid thermal annealing (RTA) experiments on crystalline and amorphous (Fe70Ga30)1−xBx films in order to understand and reduce the linewidth of ferromagnetic resonance (FMR). In the absence of cubic anisotropy in amorphous films, the effective anisotropy is small, resulting in a narrow FMR linewidth. The FMR linewidth in both crystalline and amorphous films can be further reduced by RTA. In crystalline films, a minimum FMR linewidth can be achieved by annealing the samples at a relatively high temperature for a short time. The effect is attributed to the reduction in the uniaxial anisotropy. In amorphous films, the reduction in FMR linewidth is achieved at low temperature and short annealing time. Elevated temperatures and prolong time may crystallize the amorphous structure and introduce a much large cubic anisotropy, resulting in a large FMR linewidth.