bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recording characteristics of perpendicular magnetic recording medium using a stretched‐disk interface
Authors: Uchiyama Hiroshi , Honda Naoki , Oyanagi Eiki , Kawano Norikazu , Urakawa Yoshiyuki 
Published: July 2007

AbstractThe FM and digital recording performance of a stretched disk system with a good interface between a perpendicular magnetic recording medium and an MIG‐type ring head has been examined. Little evidence of the low‐frequency enhancement and high‐frequency suppression effect has been found in a short wavelength FM recording. No reversal noise was detected at a carrier wavelength of 0.3 μm in a short wavelength static image recording. However, a harmonics distortion and a cross‐modulation distortion were found to be significant and are believed to be due to a sharp transition of the magnetization direction of the medium, which is not suitable for two‐signal multiplex recording.On the other hand, the error rate of digital recording is found to depend on signal‐to‐noise ratio (SNR) for a longer wavelength and a peak shift pattern for a short wavelength recording. The error rate better than 10−4 was obtained by using PRIV coding at 0.88 μm2/bit (Tw = 5 μm, λ = 0.35 μm). This result demonstrates the applicability to a high‐density recording. By improving a frequency response of a head and medium and by optimizing further pulse slimming, the wavelength limitation for error rate due to a peak pattern shift can be improved more.
High‐density magnetic tape recording by a nontracking method
Authors: Himeno Takuji , Tanaka Masato , Katoku Takashi , Matsumoto Kissei , Tamura Masafumi , Min‐Jae Han , Sasaki Toshikazu , Ito Jota 
Published: July 2007

AbstractConventional high‐density digital recording using a rotary head requires a high‐accuracy servo system with a high precision in mechanics. By combining double‐track scanning and data rearrangement, a nontracking method by which all data can be reproduced in order has been developed. By using this method, it is shown that a tracking accuracy of ± 100 μm for a track pitch of 9.8 μm is obtained compared to a conventional value of ±5 μm. A stamp‐sized cassette and a compact digital audio tape recorder are developed using this nontracking method and evaporated metal tapes.
Magnetic force microscopy for high‐density point magnetic recording
Authors: Ohkubo Toshifumi , Yanagisawa Keiichi , Kaneko Reizo , Kishigami Junichi 
Published: July 2007

AbstractA scanning probe microscope (SPM) which can depict physical properties by scanning a sharp tip onto the surface of a material of interest has recently been developed. Further intensive work is being carried out for imaging finer patterns in an attempt to apply its technique to high magnetic recording density.This paper considers a magnetic case and very fine bits are written in a Co‐Cr/Permalloy perpendicular medium by using a very sharp tip of a magnetic material and then detected by the same tip. As one attempt to increase recording density, a bidirectional field recording scheme has been examined where an overwriting was performed. The recording density in connection with a detection signal (magnetic field gradient) is discussed.Based on a systematic experiment using various radii of the tips, the recording density in the bidirectional case was found to be twice that for a unidirectional field recording. The linear density of 4000 ‐ 5000 fr/mm and the bit‐line width of about 500 nm were confirmed.
Influence of plating bath treatment on characteristics of non‐electrolytically plated metal film resistors
Authors: Aoki Hiroo , Moriyama Minoru 
Published: July 2007

AbstractA plated metal film for a resistor with medium resistance around 1 kω is too thin to achieve reproducibility in the characteristics. However, it was found that if the oxygen content in the plating solution is reduced by boiling and feeding nitrogen gas through the solution, the plating time is reduced and the reproducibility of the resistance is improved.It was found also that as the aging period of the plating solution increases, the plating efficiency increases. The damp proof, initial resistance distribution, current noise, thermal coefficient of resistivity (TCR), and resistance change before and after thermal treatment of the resistive films plated in a nitrogen gas‐bubbled solution with low oxygen content are superior to those of resistive films plated in untreated solution. The superior properties of resistors plated in the modified plating solution are due to a more uniform film thickness. However, the short period load characteristics of the resistors plated in the modified and nonmodified solutions exhibit no difference.
Desired mode excitation by power additive signal injection in a multiple‐device cavity combiner
Authors: Tanaka Satoshi , Nogi Shigeji , Fukui Kiyoshi 
Published: July 2007

AbstractThis paper describes the elimination of undesired mode suppression in a multiple‐device cylindrical cavity combiner caused by the effect of excitation of the desired power‐combining mode due to external signal injection. Mode analysis is carried out to derive the condition of undesired mode suppression and of sustaining the desired mode oscillation and to prove the capability of perfect combining of the output powers of the multiple‐device structure and the power of injected signal. Experiments with TM020‐mode cavity confirmed the theory.
Finite element analysis of excitation and transmission problems of magnetostatic forward volume wave
Authors: Hano Mitsuo , Kondo Motomi , Awai Ikuo 
Published: July 2007

AbstractA finite‐element formulation is described and some numerical results are presented for excitation and transmission problems of magnetostatic forward volume wave. The governing equation for the vector potential is obtained through Maxwell's equations under the magnetostatic approximation.First, numerical results for radiation impedances of the magnetostatic wave agreed well with analytic solutions. Second, the reflection and transmission characteristics of the magnetostatic wave for a metal strip are analyzed. The reflection coefficient changes periodically with the width of the conductor and its periodicity agrees with a wavelength of the magnetostatic wave. In the case of a narrow strip, the interaction of evanescent waves becomes significant, resulting in a finite reflection coefficient when the width approaches zero.
Nanometer‐fabrication process and ghz‐range low‐loss saw filters
Authors: Yamanouchi Kazuhiko , Lee Chang‐Soo 
Published: July 2007

AbstractRecently, the frequency range allocated to mobile communication has been extended to the gigahertz band (quasi‐microwave). The filters used in RF stages for this high‐frequency application require wide bandpass characteristics and must have ample attenuation outside this bandpass frequency.This paper describes the fine lithography technology necessary for fabricating surface acoustic wave devices used at the gigahertz band and also a low insertion loss surface acoustic‐wave (SAW) filter.
Reliability improvement of polyimide‐insulated al‐alloy interconnection against package resin shrinkage stress
Authors: Sakuma Noriyuki , Homma Yoshio 
Published: July 2007

AbstractNew methods to reduce the deformation failure of the polyimide‐insulated multilevel interconnection and nondestructive measuring method to estimate the failure are presented. Deformation failure of the interconnection was found to be detected more sensitively by electrically measuring yields of via‐chain patterns of the two‐level interconnection located around test chip corners than by observing the first‐level Al‐alloy line deformation directly. Reduction of the alloy line failure was examined by analyzing which part of the resin causes the shrinkage stress which in turn causes the alloy line failure. It is shown that both improving the package resin adhesion to the LSI chip and using a resin with a smaller thermal expansion coefficient were remarkably efficient in reducing the alloy line deformation failure.
Admittance characteristics of au/p‐si schottky diode with damage induced by reactive ion etching
Authors: Asai Akira , Ohachi Tadashi , Taniguchi Ichiro 
Published: July 2007

AbstractReactive ion etching (RIE) is known to alter electrical characteristics by creating a damaged layer on the surface of the etched substance. An Au/p‐Si Schottky diode was formed on a silicon surface which was etched by RIE using CF4 gas. It was found that excess dc conductance and inductive susceptance were observed in the current voltage (I‐V) and the admittance frequency (Y‐f) characteristics under forward bias conditions, respectively. These results are explained by assuming the existence of deep‐level traps induced by RIE in the depletion region of the diode. Assuming a damage depth distribution of 10 nm, the experimental values of inductive susceptance are able to calculate by following parameters of the deep‐level traps induced by RIE; Er ‐ Ev = 0.33 (eV) and NT = 1 × 1019 (cm−3).
Tantalum electrolytic capacitor employing polypyrrole as solid electrolyte
Authors: Yamamoto Hideo , Fukuda Minoru , Isa Isao , Yoshino Katsumi 
Published: July 2007

AbstractThe conventional tantalum electrolytic capacitor is made by anodically oxidizing sintered porous tantalum metal powder to form tantalum oxide film, followed by precipitating manganese dioxide by thermal decomposition of the tantalum oxide film soaked in manganese nitrate solution. The electrical conductivity of manganese dioxide is as low as 10−2 to 10−1 S/cm, and manganese dioxide is poor in its electrical property, in particular, the high‐frequency characteristic.In this paper, a precoating layer with a slightly higher resistance is used. The polypyrrole film is deposited by electrolytic polymerization using the precoating layer as the anode. It is found that the capacitor with polypyrrole formed by chemical oxidative polymerization has superior electrical properties compared to the capacitor formed by using manganese dioxide instead of a precoated layer. Using hydrogen peroxide as the oxidizer for chemical oxidative polymerization, polymerization of pyrrole can be achieved even inside the sintered body and the electrical conductivity and thermal stability of the polymer were excellent. The resultant capacitor has excellent electrical and temperature characteristics, its lifetime is long, and it can be surface‐mounted.
Analysis of overwrite mechanism in magnetic recording
Authors: Itoh Kenya , Tagawa Ikuya , Nakamura Yoshihisa 
Published: July 2007

AbstractAlthough there is a necessity to achieve excellent overwrite (O/W) in magnetic disk write‐read equipment, the O/W mechanism has not been clarified sufficiently. Accordingly, the investigation of the O/W mechanism by experiment and by a finite element method simulation incorporating a magnetization model has clarified that during O/W, not only the field of the head but also the field generated by the magnetization distribution of the medium (inside field) and rewrite action exert influence on O/W characteristics. From the fact that the inside field changes with the recording density of the signal, modeling was done on the write density dependence of O/W characteristics and verification was made by simulation and experiment.Moreover, from the viewpoint of O/W, a comparison was made of perpendicular magnetic recording and longitudinal magnetic recording. As a result, for the combination of ring head and longitudinal film medium, although the O/W characteristics are degraded with the increase of the O/W signal recording density, in perpendicular magnetic recording the experimental result that the O/W erased value takes a maximum value when the recording density of the overwrite signal is half that of the prerecorded signal in perpendicular magnetic recording is obtained. Thus, it became possible to clarify the mechanism by using a model taking into consideration the inside field.
Frequency stabilization of a semiconductor laser using the faraday effect of the saturated absorption spectroscopy signal of rb atoms
Authors: Ueno Takashi , Nakazawa Takao , Nakano Hiroyuki , Sato Takashi , Shimba Minoru 
Published: July 2007

AbstractTo stabilize the oscillation frequency of a semiconductor laser by using an absorption spectrum of atoms and molecules as a frequency reference, modulation of an injection current of the laser has commonly been adopted since it gives a high detection sensitivity. However, as a result, the oscillation frequency becomes broadened, which is a drawback.To overcome this difficulty, a new method has been proposed which utilizes the modulation scheme resulting from the Faraday effect of Rb atoms and thus no direct modulation is needed. In a conventional method using a normal absorption spectrum, detection sensitivity is limited by a spectrum broadening due to the Doppler effect. The stability has been improved one order of magnitude by using a saturated absorption spectroscopy method, compared to the conventional method. Also, with this method, a number of stabilized frequency points is increased. An oscillation frequency can be controlled by changing the dc magnetic field for the Faraday effect modulation for a frequency range over about 8 GHz around the frequency corresponding to Rb‐D2 lines.
Analysis of nonreciprocal phase characteristics of magneto‐optic channel waveguides using finite‐element method
Authors: Zhuang Xiu‐Ping , Koshiba Masanori 
Published: July 2007

AbstractTo evaluate nonreciprocal phase characteristics of a magneto‐optic channel waveguide, the formulation of a finite‐element method based on a scalar wave approximation is discussed here for the first time. This problem is ascribed to the problem of solving a nonlinear eigenvalue equation. However, a simple iterative method is proposed here for solving the nonlinear eigenvalue equation. The validity and usefulness of the present method are demonstrated in analyzing magneto‐optic rib waveguides and magneto‐optic ridge waveguides. A discussion to increase a nonreciprocal phase shift in those waveguides also is given.
Evaluation of heating condition for collapse of fluoride glass tubes
Authors: Sakaguchi Shigeki 
Published: July 2007

AbstractA heating condition for the collapse of fluoride glass tubes is examined, and a thermal history is discussed. So far, theoretical discussions on the collapse have been made only for the case of a contraction along a tube‐radial direction as a viscous flow of glass. This paper discusses an evaluation method of a contraction along not only the radial but also axial directions by taking into account the effect of heat source traverse. The evaluation is made by numerically solving simultaneous equations, a thermal conduction equation and a viscous flow equation. The method provides the information of a thermal history time temperature relation. Heating conditions are discussed for various traverse speeds and temperature profiles of a heating source. Based on the thermal history thus obtained, the distribution of crystallites grown in a glass is calculated. An excess scattering loss after a collapse is estimated.
A method for analyzing properties of rectangular waveguides of steeply tapered width
Authors: Suga Takashi , Ishihara Fujio 
Published: July 2007

AbstractA method is described for calculations of the characteristics of the tapered waveguide by means of the electromagnetic field method (normal mode expansion method) in which many higher‐order modes are taken into account. The tapered waveguide to be treated is assumed to be straight along the axis and its thermal loss is assumed negligible. The shape is such that the generated higher‐order mode sequence contains only one parameter. (As an example, either m or n is constant in the TEmn modes.) In the eigenmode analysis of such a tampered waveguide, it is possible to derive solutions which agree with the rigorous solutions taking into account the infinitely many higher‐order modes with sufficient accuracy in practice by means of an application of the extrapolation with relatively few higher‐order modes. The validity of the results is confirmed by experiments. The present method can be applied to a structure in which the slope of the taper is almost 90° (or a step shape) so that it has a wide application range.
Microcrystallization process of hydrogenated amorphous silicon films
Authors: Motohashi Mitsuya , Kashu Akiko , Homma Kazuaki , Fukami Toyoji 
Published: July 2007

AbstractThe interface barrier height at the a‐Si:H/a‐SiO:H interface to hydrogen increases with the microcrystallization of a‐Si:H. In this study, using the fact that the barrier height is dependent on the hydrogen effusion characteristic, the microcrystallization time of a‐Si:H was measured.
Zno thin films prepared by rf magnetron sputtering method on sio2/si substrate
Authors: Takada Syuichi , Fujinaka Masaharu 
Published: July 2007

AbstractA zinc oxide (ZnO) thin film was formed by RF magnetron sputtering and the dependencies of the crystallinity, optical propagation characteristic and electrical resistivity of the film on the substrate temperature during film deposition were investigated.The ZnO film crystallinity was excellent and the standard deviation of the angle in the X‐ray rocking curve which represents the sharpness of the c‐axis orientation was less than 1°. The crystallinity was improved and the film resistivity decreased from 107 to 102 Ω ± cm as the substrate temperature increased.The optical propagation loss was around 1.78 dB/cm for the TE0 mode. It was concluded that not only the film orientation but also the film density must be taken into account to achieve a ZnO film with good optical propagation characteristic.
Circuit theoretical study on the lifetime of the resonant state
Authors: Ohtani Naoki , Sanada Hirofumi , Nagai Nobuo , Suzuki Masakiyo , Miki Nobuhiro 
Published: July 2007

AbstractWith a view to investigating the operating speed of a quantum effect device, considerable work has been carried out on the lifetime of the resonant state. The lifetime of the resonant state in a multiple barrier structure is defined as the time constant with which the existence probability of the electron is attenuated. This is a quantum theoretical transient phenomenon.In this paper, by means of a complex‐valued equivalent circuit proposed previously by the authors, this transient problem is discussed from a circuit theoretical viewpoint. First, the complex frequency variable (Laplace variable) is related to the complex energy which permits a circuit theoretical investigation on the lifetime. It was found that the real part of the complex frequency, which makes zero the sum of the admittances looking to the left and the right, corresponds to the lifetime. By means of a numerical experiment, a double‐barrier structure is studied and compared with the research results reported previously. The error of the lifetime estimated from the half‐value width also is studied. In addition, a symmetric triple barrier structure is studied. It is found that a lifetime exists that cannot be estimated from the half‐value width.
Generalized rat‐race circuit with an arbitrary power‐split ratio
Authors: Ohta Isao , Kawai Tadashi 
Published: July 2007

AbstractA rat‐race circuit consists of four constituent transmission lines whose length at the center frequency is an odd multiple of one‐quarter wavelength. One of these four lines is designed to have a difference in length by an odd multiple of one‐half wavelength in comparison to the remaining three. Especially, the circuit made of three one‐quarter wavelength transmission lines and one three‐quarter wavelength line with a total length of 3/2 wavelengths has been used most widely as the basic circuit.In this paper, with a view to finding the general constitutive conditions for a rat‐race circuit with an arbitrary power‐split ratio, a uniaxially symmetric circuit made of transmission lines with an arbitrary length and an arbitrary characteristic impedance is treated and the relationship is found between the electrical lengths and the admittance values of each transmission line section determined by the matching condition and the power‐split ratio. It is found that a circuit design is fundamentally possible if the ring length is more than one‐half wavelength.It is shown that a power divider with an arbitrary power‐split ratio can be designed with a circuit longer than one wavelength and that there is flexibility in the choice of the admittance values and the lengths of each section for a given power‐split ratio if the ring length is constant. Further, from the practical viewpoint, the foregoing results are used for miniaturization of the circuit and for design of large differences of power division with appropriate admittance values. The theoretical results are validated by experiments.
Extended ray theory for analyzing electromagnetic scattering process on two‐dimensional smooth objects
Authors: Ikuno Hiroyoshi , Ohmori Toshiyuki , Nishimoto Masahiko 
Published: July 2007

AbstractWhen the field scattered by a cylindrical object is analyzed using a pulse of short duration, the scattered field can be observed as a pulse train with appropriate propagation times for responses containing information on the polarization direction of the incident wave, object shapes, and materials. By analyzing and discriminating these pulses, the scattering phenomena can be resolved. In the present study, an extended ray theory (ERT) is proposed as a method to systematically analyze the scattering process of the electromagnetic wave by a smooth two‐dimensional object.Here, it is demonstrated that the scattering process of the electromagnetic wave can be represented by six elementary processes. For the analysis of these elementary processes, two charts are constructed on the geometrical optics ray and the diffraction ray by means of the ray‐tracing technique. It is shown that the use of these charts can evaluate the scattered field including the contribution from the complex ray in the caustic shadow region in addition to the real ray. In fact, to verify this theory, the propagation times of the scattered rays from the real scattering center and the complex scattering center extracted from the charts were computed. When the transient responses are analyzed based on the results, it was possible to explain all response waveforms in terms of the contribution from the real and complex geometric rays and the diffraction rays.
Asymmetry analysis of two‐dimensional optical phase‐modulation characteristics of a microchannel spatial light modulator (MSLM)
Authors: Hori Terushige , Toyoda Haruyoshi , Hara Tsutomu 
Published: July 2007

AbstractThe two‐dimensional optical phase modulation characteristics are described for an optical address‐type microchannel spatial light modulator (MSLM). Especially, the asymmetry of the optical phase modulation characteristics is analyzed. Here, the diffraction efficiency is measured when a fringe pattern is written into the device in addition to the optical phase modulation of the MSLM. The results obtained are an optical phase modulation of 2π radian and a diffraction efficiency of about 17 percent. This is believed to be caused by the change of index of refraction due to the lateral electric field at the boundary between the bright and dark patterns. Also shown is the result of the correlation experiment using this characteristic effectively.