Search

This study reports on the performance of a thin-film magnetic sensor that uses impedance change at a high frequency. A closed magnetic circuit, a strip pattern for the magnetic films, and an NiFe/SiO2 multilayer film structure were adopted for high sensitivity and large voltage change. A voltage change ratio of 50-60% was achieved by applying an external field of several Oe with an AC carrier of ∼800 MHz. The sensor was confirmed to perceive a highfrequency external field as an amplitude modulation of the AC carrier voltage, and exhibited broad frequency bandwidth, high linearity, and no hysteresis or Barkhausen noise.

This study reports on the performance of a thin-film magnetic sensor which uses the high frequency magneto-impedance (HFMI) effect. In order to obtain a high sensitivity and a large voltage change ratio (/spl Delta/Vpp/Vpp(0): corresponds to the MR ratio), a strip pattern, a closed magnetic circuit, and a NiFe/SIO/sub 2/ multilayer film structure are adopted for the magnetic films of the sensor. A /spl Delta/Vpp/Vpp(0) of 60-70% is achieved by applying an external magnetic field of several Oe. Moreover there is no hysteresis or no Barkhausen noise in this sensor, which has a magnetic film width of 10 /spl mu/m. In terms of linearity, the sensor exhibits modulation degree (m) of 12% and a total harmonic distortion (THD) of 0.8%. >

Large-capacity, high-speed removable memory can provide portability of information and working environment. The ISO/IEC committee has started work on establishing enlarged-capacity standards for magneto-optical disks and phase-change disks. Both have direct overwriting function. This paper explains present technological status and future standardization plans.

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 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 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.

Manufacturing narrow track magnetic heads is difficult as track widths become very narrow. A new flying-head manufacturing method is established by applying ion-etching. Optimum conditions for ion-etching of the ferrite material were determined. More than 10 μm ion-etched depth and even less than 5 μm track width were obtained. Through experimental and theoretical evaluation, it is proven that ion-etched heads have equivalent or better read/write characteristics than mechanically manufactured heads.

This paper discusses fundamental characteristics of a single‐grid ion‐beam sputtering system as well as indicating the optimum aperture dimensions and transparency of a grid. With an optimum thickness and aperture size, a high deposition rate of over 90 nm/min and a grid lifetime of over 10 h were obtained at an accelerator voltage of

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.

An improved ferrite ion etching technique and the characteristics of magnetic heads fabricated by this technique are reported. To improve the read/write characteristics of the head fabricated by ion etching, the optimum conditions have been investigated, under which the maximum etching rate ratio between ferrite sample and metal mask can be obtained. As a result, it has become possible to realize etching grooves deeper than 10 μm by sputter etching using a thin, high definition Ti or Al mask laminated with Cr. Using this improved ion etching technique, narrow track width magnetic heads can be fabricated with tolerances within ±1 μm and improved yield rate.

The magnetic properties of NiFe films in the thickness range of 1 to 3 μm prepared using ion-beam sputtering were investigated by varying parameters such as the grid system, composition ratio of the targets, accelerator voltage and the beam current bombarding the substrate. The effects of the ion-assist voltage and ion-assist current on magnetic and electrical properties were investigated and the deposition conditions for NiFe films with low coercive force and resistivity were clarified. Due to their optimization of the ion-assist voltage and current, the ion-beam sputtered NiFe films have the low coercive force and resistivity necessary for thin film head applications.

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.

New methods for manufacturing a floating thin film magnetic head and its characteristics are reported. Simple formulation of the floating thin film magnetic head was attempted by using process not requiring glass bonding technique and by using ion etching method to form the slider surface (air bearing surface), which was formed as a negative pressure slider. The processes comprise forming thin film 4+4 turn transducers on a ferrite or ceramic substrate whose thickness is equal to the slider length, cutting, lapping, ion etching the slider surface to the form of a negative pressure slider, and cutting to the individual core. Results attained show that the present methods are much simpler than former floating thin film magnetic head manufacturing methods. Moreover, it is proven that the head floating characteristics are much better than for the former floating thin film magnetic head. The read/write characteristics for the present head are comparable with characteristics of thin film heads reported previously.

To converge a laser beam parallel to the junction plane, a taper ridged waveguide is fabricated at the tip of the laser diode cavity. The beam converging effect is observed, and the beamwidth parallel to the junction plane is reduced to 1μm

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.