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The surface resistance of high-Tc superconducting c-axis oriented EuBa2Cu3Ox thin film sputtered on MgO is greatly lowered by reducing in-plane misorientation. A coplanar delay line with the delay time of 6.1 nsec and a insertion loss of 0.03 dB/nsec at 77 K and 1 GHz are fabricated using the EuBa2Cu3Ox thin film. We summarize recently reported data on high-Tc superconducting resonators, bandpass filters and delay lines.

This paper reports on the properties of superconductive 40 cm delay lines fabricated using EuBaCuO films and several new techniques. The insertion loss is 0.068 dB/nsec at 77 K and 1 GHz, and the delay time is 4 nsec independent of frequency. The reflection coefficient and VSWR are less than -15 dB and 1.5 at frequencies below 3 GHz.

The influences of oxygen plasma on critical temperature and critical current density are studied using BiSrCaCuO micropatterns. Although a large critical temperature degradation as well as a slight decrease in a critical current is observed in 1.5–20 μm wide microbridges that have been put into an oxygen plasma, the critical temperatures are recovered by reducing excessive absorbed oxygen. Additionally, these recovered microbridges have higher critical current densities, whose improvement strongly depends on the microbridge width, 5–30 times than those without oxygen plasma treatment.

We report the properties of disk resonators and end-coupled disk filters. High quality factors of 60,000 at 3 GHz and 27,000 at 7 GHz, respectively corresponding to TM11 and TM31 modes, were confirmed in a Nb disk resonator with a diameter of 18 mm on a sapphire substrate. End-coupled three-pole disk filters were also fabricated using the 7-mm-diameter Nb disks (TM11 mode). The disk filter with frequency of 7.5 GHz, fractional bandwidth of less than 1%, and insertion loss of less than 0.7 dB exhibited higher power handling capability of up to 22.5 dBm (180 mW). This high capability is thought to be achieved by reducing the current concentration at the edges of each resonators.

This letter reports the properties of 1.5-GHz band-pass microstrip filters fabricated using EuBacuO superconducting films. Although 3- and 4-pole filters constructed using a superconductor and a silver ground plane exhibited good reproducibility and very low insertion loss of 3∼5 dB at 70 K, in comparison with Cu filters with 16∼27 dB loss at 77 K, the insertion loss was almost constant at temperatures below 70 K. In contrast, the insertion loss in the 4-pole filter with a superconductive ground plane was 1.2 dB at 70 K and 0.6 dB at 28 K. The center frequency and bandwidth at -3 dB were, respectively, 1.45 GHz and 1.4% at temperatures below 70 K.

This paper describes the influence of amorphous fluoropolymer (AF) film on the properties of high-T c superconductive microwave components, when it is used for surface protection and as a spacer. It is found that AF film can protect EuBaCuO and TlBaCaCuO superconducting film from dampness, thus maintaining the properties of a microstrip resonator for at least 1000 h. The AF protection has almost no effect on properties such as temperature dependence and unloaded-Q values in high-Q microwave components. Additionally, the use of AF film as a spacer in a strip-line structure reduces the influence of spacing on the effective dielectric constant and characteristic impedance.

This paper reports on the properties of superconductive strip-line resonators fabricated using EuBaCuO superconducting films on MgO (100) substrates. A high loaded-Q of 22000 and an unloaded-Q of 24000 are realized at 35.5 K and 5.55 GHz. The surface resistance is calculated as 160 µΩ without any correction and 50 µΩ with t/λ correction. In addition, a resonant frequency shift of 40 MHz occurs in the measurement range. This shift can be mainly explained by the reduction in penetration depth due to the decrease in temperature. From this shift, penetration depth at 0 K is estimated to be 0.75 µm. Furthermore, there is no change in the unloaded-Q in the power region below -10 dBm, but then the unloaded-Q gradually decreases as the input power is increased although the penetration depth hardly varies. This limitation does not indicate that the whole superconductive phase is weakened. The influence of air spacing on resonant frequency is also discussed for MgO and LaAlO3 substrates.

This paper investigates the in-plane magnetic anisotropy of Fe/SiO2 multilayer film. Fe/SiO2 film exhibits field-induced uniaxial anisotropy which depends strongly on the Fe and SiO2 layer thickness. Maximum uniaxial anisotropy leads to minimum coercivity. The interfaces between Fe and SiO2 layers deteriorate uniaxial anisotropy. There is no correlation between the anisotropy field and magnetostriction. No in-plane anisotropy of the film stress, crystal orientation, or crystal grain shape is observed in Fe/SiO2 film prepared with an external field. Also, the Fe layer maintains the same atomic state as bulk-Fe. The multilayering effects, such as magnetostatic coupling between Fe layers and small crystal grains, play an important role in making anisotropy dispersions small, and enhancing the uniaxial anisotropy of Fe layers in Fe/SiO2 film.

This letter reports on localized orientation control in BiSrCaCuO superconducting films. Uniformly oriented crystals, of which the c-axis exists in-plane, were grown on a MgO (110) plane by annealing them in contact with a MgO (100) plane. Thus, stripe patterns including oblique tapers in stripe edges were fabricated on MgO (100) crystals to produce locally appearing (110) planes. By annealing them in contact with a MgO (100) plane, the uniformly oriented crystals were confirmed to grow around oblique tapers in stripe edges fabricated on MgO (100) crystals.

Grandite garnet from the Kamaishi mine are subdivided into three types “A”, “B1” and “B2”. The garnet “A”, crystallized in the earlier stage, is always isotropic and has the composition ranging from And28Gro72 to And67Gro33. Birefringence of the garnet “B1”, which is commonly zoned, decreases from about 0.01 to zero with increasing of the andradite mol.% ranging from 46 to 100. The garnet “B2” whose compositional range almost agrees with that of the garnet “A” is characterized by a maximum birefringence (about 0.004) at And40Gro60. It is suggested that the garnet “B2” have been formed during a stage between those of the garnet “A” and “B1”, or recrystallized from the garnet “A” during the crystallization of garnet “B1”. The refractions and birefringence of garnet And50Gro50 calculated using the rhombic cell model and Lorentz formula are α=1.806, β=1.811, γ=1.819 and γ–α=0.013; the optical orientation is a=X, b=Y and c=Z.

This paper reports the result of experimentally investigating the magnetoresistance effect in Ni–Fe films formed by ion beam sputtering (IBS). Although IBS‐formed Ni–Fe film has a well‐defined uniaxial magnetic anisotropy and high permeability, its magnetoresistance effect is smaller than that of film formed by radio‐frequency (rf) sputtering. This small magnetoresistance effect was found to be caused by an increase in film resistivity rather than by a decrease in magnetoresistivity. The increase in resistivity cannot be explained merely by impurity concentration; it is also due to defects produced by Ar+ ion bombardment and the impingement of particles with relatively high energies. When the substrate temperature was higher than 220 °C, the resistivity became smaller as the substrate temperature was increased because of both having larger crystal grains and recovery of defects.

This paper discusses a systematic investigation on the magnetic properties of multilayer films consisting of only Fe and nonmagnetic layers (Al2O3, Cu, C, Si, and Ti). Magnetostriction increases and becomes nearly zero as the Fe layer becomes thinner, regardless of the nonmagnetic species. In Fe/Al2O3 and Fe/Cu multilayer films, the magnetostriction increase is thought to be caused by the change in crystal preferred orientation of the Fe layers. By contrast, in Fe/C, Fe/Si, and Fe/Ti multilayer films, the increase is caused by the balance in positive and negative magnetostriction. Additionally, a low hard‐axis coercivity of approximately 1 Oe and a relative permeability of more than 1000 can be achieved in Fe/Cu, Fe/Al2O3, and Fe/C multilayer films. These soft‐magnetic properties are thought to be caused by the weak crystalline magnetic anisotropy due to small crystal grains and the magnetostatic coupling between Fe layers.

This paper reports on the results of experimental investigation into the preferred orientation of Ni–Fe film formed by ion beam sputtering. Through experiments concerning ion bombardment and substrate temperature, argon ion bombardment is found to increase the amount of the (111) crystal texture in addition to contributing to the texture orientation itself. In terms of film morphology, the fracture cross section indicates a more obvious columnar structure with the film surface becoming slightly rougher as the amount of argon ion bombardment increases. Conversely, nitrogen and oxygen‐mixed ion bombardment weakens the (111) preferred orientation, and the effect becomes more notable when the ion has a higher energy. On the other hand, although the substrate temperature increase makes the (111) texture better oriented, the amount of the crystal texture becomes smaller due to this temperature increase. Additionally, the observed lattice distortion corresponds well to that estimated by the internal stress.

This paper discusses the magnetic properties of ion‐beam‐sputtered Fe/SiO2 multilayer films. Decreasing Fe layer thickness, while maintaining a constant SiO2 layer thickness, results in good soft‐magnetic properties and nearly zero magnetostriction. These results are thought to be due to smaller crystal grains and a change in crystal orientation in the Fe layers. In Fe/SiO2 multilayer films consisting of 7‐nm Fe and 2.5‐nm SiO2 layers, magnetization of 1.55‐T, hard‐axis coercivity of 0.3 Oe, and relative permeability of 4000 are achieved under magnetostriction of less than ±10−6. After 250 °C annealing, relative permeability increases up to 5000. Furthermore, a magnetic domain structure with easy‐axis direction and extended 180° walls suitable for thin‐film heads can be obtained.

This paper presents an experimental investigation on the magnetic anisotropy and heat stability in Ni/Fe artificial lattice films. Magnetic anisotropy is found to increase as the lattice period and the Fe layer thickness decrease. The annealing of Ni/Fe films is shown to decrease hard‐axis coercivity to 0.3 Oe. However, annealing at temperatures above 400 °C causes an increase in coercivity, perfect alloying of the Ni/Fe film, and recovery of the crystallinity of the Fe layer sandwiched between Ni layers. In the Ni/Fe (2/10 nm) film, very small magnetostriction and large saturation magnetization are maintained up to 350°C. A prototype thin‐film head with a Ni/Fe yoke shows stable conventionally reproduced signals for small write currents, superior overwrite properties, and good heat stability at annealing temperatures below 300 °C.

This paper reports the results of experimental investigation into the angular distribution of sputtered particles in ion beam sputtering. A Ni–Fe alloy target that includes many cones wherein the composition is several percent Fe‐richer than in the matrix, is bombarded by Ar+ ions at 1 keV at various ion incident angles. As a result of this experiment, it is found that the characteristics of the Ni fraction for the collector angle become asymmetric and the maximum Ni fraction in the film approaches the Ni fraction of the alloy target as the ion incident angle increases. From a simple model analysis, these tendencies are found to be explained by the interaction between the oblique ion incidence and the surface topography including segregation.

This paper reports the results of experimental and analytical investigations into the properties of ion‐beam‐sputtered Ni/Fe artificial lattice films. Through structure analysis, it is known that the Fe layer has poor crystallinity and the Ni layer has a face‐centered‐cubic structure with strong preferred orientation. Additionally, the Ni/Fe lattice film is found to possess good soft‐magnetic properties with lower coercivity less than 1 Oe and uniaxial anisotropy as the lattice period is decreased. The saturation magnetization and magnetostriction are also confirmed to be controlled by changing the lattice period and the thickness of Ni and Fe layers. As a result of the simplest model analysis, the very small magnetostriction obtained in this experiment is thought to be realized by the balance in magnetostriction among Ni, Fe, and Ni‐Fe interdiffusion layers. Furthermore, a good domain structure is observed in the Ni/Fe lattice film with very small magnetostriction.

This paper reports results of experimental and analytic investigations concerning the Ni–Fe film composition formed by ion beam sputtering under various forming conditions. From experiments involving the substrate angle and temperature that had dramatic influence on the Ni–Fe film composition, it is found that the primary Ar+ ion bombardment dominates the composition variation. Also, the Ni fraction in Ni–Fe film and its deposition rate decrease as the ion current density increases. As a result of simple analysis, this composition variation is found to be caused by preferential resputtering. Conversely, the Ni fraction increases as the substrate temperature increases without a deposition rate change under primary ion bombardment. This phenomenon cannot be explained only by preferential resputtering. It also includes the formation of an Fe‐rich layer on the film surface.

This paper reports on the systematical investigation into the magnetic properties of Fe/Co, Fe/CoFe, and (Fe/Co)/SiO2 multilayer films. Magnetostriction in Fe/Co and Fe/CoFe films can be controlled by changing the thicknesses of the layers. The Fe/Co film (10/0.5 nm) shows saturation magnetization of more than 2 T and hard‐axis coercivity of 1.5 Oe for magnetostriction near zero. The hard‐axis coercivity is decreased to 0.8 Oe by 300 °C annealing. A magnetic domain structure suitable for a thin‐film head is also established for this film. Additionally, a hard‐axis coercivity of less than 1 Oe, a relative permeability of 2000, and a saturation magnetization of approximately 2 T are achieved in (Fe/Co)/SiO2 film [(15/0.5)/5 nm] with no annealing. A controlled domain structure consisting of extended 180° walls is observed in this film.

This paper reports on the results of an experimental investigation into the magnetic properties of iron films formed by ion beam sputtering. Through the iron film formation at various nitrogen partial pressures and substrate angles, nitrogen ion bombardment is found to reduce the coercive force of the magnetic hard axis in addition to inducing uniaxial anisotropy. The decrease in the coercive force corresponds well to the increase in the nitrogen concentration and the anisotropy constant of the α‐Fe‐composed films. The uniaxial anisotropy is confirmed to mainly result from directional ordering rather than crystalline anisotropy. The magnetic properties of the film having well‐defined uniaxial anisotropy are a coercive force of 0.3 Oe, a saturation magnetization of 2.2 T, an anisotropy field of 3.5 Oe, and a permeability of 5000.

This letter reports on the magnetic properties of Fe/Co and Fe/CoFe multilayer films. A zero magnetostriction is realized by changing the thickness of each layer. In addition, Fe/Co films with high magnetization of more than 2 T and good soft‐magnetic properties of 1.5 Oe coercivity are confirmed. By 300 °C annealing, the hard‐axis coercivity in Fe/Co films decreases to 0.8 Oe. Furthermore, a suitable magnetic domain structure for a thin‐film head is confirmed, and the structure is found to be determined by the total magnetostriction.

This paper reports the results of experimental investigations into the chemical shifts of Fe 2p, Ni 2p and N 1s in Ni-Fe alloy and Fe films. Through XPS analysis on Ni-Fe film composition, it is known that the binding energy of Fe0 2p increases and the satellite around 859 eV shifts toward lower binding energy with an increasing Ni fraction, instead of a Ni core level shift. Additionally, Fe species are confirmed to be more preferentially oxidized than those of Ni in the Ni-Fe alloy surface. Furthermore, an observed core level shift of N 1s infers that N in iron films formed in nitrogen atmosphere chemically reacts with Fe species even though these films were not made up of iron nitrides.

This paper reports results of experimental investigations on composition variations in Ni-Fe films formed by ion beam sputtering. The composition variations, depending on both substrate angle and temperature, are caused by high energy Ar+ ions. The Ni fraction in Ni-Fe film and its deposition rate decrease as the ion current increases; this is because of preferential resputtering. Conversely, the Ni fraction increases as the substrate temperature increases without deposition rate change under Ar+ ion bombardment; this has not previously been reported.

This paper reports the results of experimental investigations into the physical and magnetic properties of Ni/Fe artificial lattice films. Through a structure analysis of Ni/Fe lattice films, it is found that the Fe layer has poor crystallinity and the Ni layer has a face-centered cubic structure with strong preferred orientation. Additionally, it is known that the Ni/Fe lattice film acquires good soft-magnetic properties with small coercivity and uniaxial anisotropy as the lattice period is decreased. Saturation magnetization and magnetostriction are confirmed to be controlled by changing the lattice period and the thickness of Ni and Fe layers.

This paper reports on the improvement of the surface flatness on BiSrCaCuO films. By keeping the film surface in contact with a MgO(100) plane during annealing, it is possible to greatly improve the surface flatness at each annealing temperature. The smooth surface is mainly made up of several-µm platelike crystals approximately 60 nm thick. The average surface roughness is determined by the annealing temperature, regardless of film thickness, in the range of 0.1–1.5 µm. As the critical temperature and surface morphology change due to the contacted MgO crystal plane, the improvement of surface flatness is considered to result from the crystal growth restriction on the film surface in contact with a MgO(100) plane.