bluuebunny/crossref_metadata_2025 huggingface dataset:
Light Detection by Superconducting Weak Link Fabricated with High-Critical-Temperature Oxide-Superconductor Film
Authors: Nishino Toshikazu , Nakane Hideaki , Tarutani Yoshinobu , Hirano Mikio , Aida Toshiyuki , Kominami Shinya , Kawabe Ushio
Published: November 2005

The light-induced changes in the current-voltage characteristics are studied for a superconducting weak link fabricated with a polycrystalline YBa2Cu3O7-δ film. The maximum superconducting current decreases by exposure to light at temperatures up to 77 K. The sensitivity of the light detection is enhanced by the use of a photoconductive semiconductor film on the surface of the weak link.
Electrical, Magnetic and Superconducting Properties of High-Tc Superconductor (Y, Sc)-(Ba, Sr)-Cu Oxide
Authors: Oota Akio , Kiyoshima Yoshio , Hioki Tatsumi
Published: November 2005

The superconductivity above 77 K occurs in (Y1-x
Sc
x
)0.4 (Ba1-x
Sr
x
)0.6Cu oxide with 0≤x≤0.2, where T
c decreases from 92 to 83 K by increasing x to 0.2. The samples with 0≤x≤0.2, which are nearly single phase of the YBa2Cu3O7-δ structure, have a sharp superconducting transition within 1 K, critical current density above 100 A/ cm2 at 77 K and the Meissner flux expulsion above 25% just below T
c. Their susceptibility data in normal state are analyzed by the sum of the Pauli susceptibility and the Curie-Weiss contribution. The former is suppressed by an increase of the parameter x, while the latter is enhanced.
Cyclotron Resonance of Photoexcited Holes in High Quality ZnSe
Authors: Ohyama Tyuzi , Sakakibara Kiyohiko , Otsuka Eizo , Isshiki Minoru , Masumoto Katashi
Published: November 2005

Heavy hole cyclotron resonance has been observed in ZnSe single crystals at 35 GHz using time-resolved cyclotron-resonance equipment. Holes have been created by a xenon flash lamp. The heavy hole resonance is almost isotropic and corresponds to a polaron effective mass of m
hp
*=(1.04±0.04)m
0. In addition, the polaron coupling constant αh for heavy hole is derived to be αh=0.983.
Oxygen Deficiency in Er1Ba2Cu3Oy Superconductive Ceramics
Authors: Kobayashi Takeshi , Takahashi Tetsuro , Tonouchi Masayoshi , Fujiwara Yasufumi , Kita Sadamu
Published: November 2005

A quenching experiment was done to investigate oxygen fugacity in Er1Ba2Cu3O
y
ceramics at high temperatures and to compare the results with those of Y-Ba-Cu-O system. The temperature in question was around 500°C above which the oxygen content became less, depending upon the temperature rise. This critical temperature was almost the same as reported for the Y-Ba-Cu-O system. According to the X-ray diffraction measurements, the crystalline structure departed from the orthorhombic to quasi-tetragonal phase as y decreased. The reduction of y was also accompanied with the degradation in both the superconducting and normal-conducting properties.
Optical Properties of Polycrystalline YBa2Cu3O7-δ
Authors: Wang Xiao-lei , Nanba Takao , Ikezawa Mikihiko , Isikawa Yosikazu , Mori Katsunori , Kobayashi Koichi , Kasai Kiichiro , Sato Kiyoo , Fukase Tetsuo
Published: November 2005

Reflectivity of polycrystalline YBa2Cu3O7-δ has been measured in the energy ranges from 2.5 to 0.05 eV and from 27 to 3.7 meV at room temperature. A Drude edge due to the free electron has been observed at 1.4 eV and the carrier concentration is estimated as 3.2×1021 cm-3. The observed low reflectivity suggests the two dimensional character of the free electron. Below T
c a structure has been observed around 17.7 meV (143 cm-1), from which the energy gap 2Δ is tentatively estimated as 15.5 meV (125 cm-1) at 15 K. Alternatively, the structure may be due to a transverse collective excitation.
Amphoteric Doping in Si-Implanted Undoped or In-Doped Czochralski GaAs
Authors: Warwick Colin A. , Ono Haruhiko , Kuzuhara Masaaki , Matsui Junji
Published: November 2005

We have studied the conditions causing amphoteric doping in Si-implanted Czochralski GaAs by photoluminescence and Hall effect measurements. Wafers of either undoped or In-doped GaAs were implanted and capped with either SiN
x
or SiO
x
before the activation anneal. Localized, strong amphoteric doping was observed only in SiN
x
capped In-doped wafers. In all other annealed wafers only donor activity was detected. This effect is explained by the point defect reactions due to the presence of In and the interaction of the GaAs with the capping material during annealing.
Compositional Disordering of Si-Implanted GaAs/AlGaAs Superlattices by Rapid Thermal Annealing
Authors: Uematsu Masashi , Yanagawa Fumihiko
Published: November 2005

Compositional disordering of Si-implanted GaAs/Al0.5Ga0.5As superlattices, followed by rapid thermal annealing (RTA), is investigated by means of sputtering Auger electron spectroscopy (AES) and Raman spectroscopy. The disordering was found to take place in the Si-implanted superlattices with a dose of 1×1015 cm-2, annealed at 1000°C for 4 to 30 seconds, resulting in an Al0.25Ga0.75As alloy. The Raman spectra showed that this alloy had a higher quality as the implanted samples were annealed for longer periods of time.
Possibility of Superconductivity at 65°C in Sr-Ba-Y-Cu-O System
Authors: Ihara Hideo , Terada Norio , Jo Masatoshi , Hirabayashi Masayuki , Tokumoto Madoka , Kimura Yoichi , Matsubara Toshiya , Sugise Ryoji
Published: November 2005

Transition to a zero-resistance state at 65°C (338 K) was observd in a Sr-Ba-Y-Cu-O system for the first time. A nonlinear I-V characteristic curve was observed at that temperature. The resistivity changed from 5×10-4 Ωcm to below a measurable limit of 1×10-8 Ωcm between 71 and 65°C. The zero-resistance state reminiscent of superconductivity was continued for ten days at room temperature in air. A magnetization measurement indicated a very small volume fraction of the room temperature superconducting state, if any.
X-ray diffractogram showed almost a single phase of oxygen-deficient perovskite with a trace of unidentified phase. Photoemission measurement showed the coexistence of multivalent Cu ions and a relatively low density of state at Fermi level. The superconductivity can be interpreted by the previously proposed d-hole mechanism.
A Superconducting Sub-Structure in Sintered YBaCu3O7-x Plates
Authors: Funaki Kazuo , Iwakuma Masataka , Sudo Yasuo , Ni Baorong , Kisu Takanobu , Matsushita Teruo , Takeo Masakatsu , Yamafuji Kaoru
Published: November 2005

We have measured magnetization of sintered YBa2Cu3O7-x
plates in a parallel magnetic field at 77 K. It was found that the difference ΔM in the magnetization between increasing and decreasing processes of the external field depends little upon the thickness of the plate, and it is predicted by the `critical-state' model that the difference is proportional to the thickness in a uniform specimen. The present experimental results suggest that the sintered plates consist of small superconducting sub-structures and that the superconducting connections among these sub-structures are not strong.
Self-Developing Characteristics of Nitrocellulose Exposed to Ion Beams
Authors: Yasuoka Yoshizumi , Harakawa Kenichi , Gamo Kenji , Namba Susumu
Published: November 2005

The self-developing and processing properties of nitrocellulose are investigated in comparison with other resists such as PMMA and PBS. It is found that only the nitrocellulose has the self-developing feature of the three resists, and that the self-developing rate of the nitrocellulose is independent of the polymerization grade of nitrocellulose, but is dependent on the nitrogen content in the nitrocellulose.
Multi-Wafer Growth of HEMT LSI Quality AlGaAs/GaAs Heterostructures by MOCVD
Authors: Tanaka Hitoshi , Itoh Hiromi , O'hori Tatsuya , Takikawa Masahiko , Kasai Kazumi , Takechi Masaru , Suzuki Masahisa , Komeno Junji
Published: November 2005

We report the first successful multi-wafer growth of HEMT LSI quality AlGaAs/GaAs selectively doped heterostructures by atmospheric pressure MOCVD. Highly uniform AlGaAs films with variations in thickness and doping characteristics of less than ± 2.0% and ± 1.5 %, respectively, have been grown on simultaneously revolving and rotating substrates. A trial fabrication of HEMTs resulted in threshold voltage standard deviations as small as 23 mV for E-HEMTs and 35 mV for D-HEMTs distributed over an entire two-inch wafer.
High Tc Superconductivity of rf-sputtered Er-Ba-Cu-O Films
Authors: Tonouchi Masayoshi , Yoshizako Yuji , Takahashi Tetsuro , Sakaguchi Yoshiyuki , Kita Sadamu , Fujiwara Yasufumi , Kobayashi Takeshi
Published: November 2005

High T
c Er-Ba-Cu-O superconducting films were prepared by r
f sputtering. The films revealed superconducting transition temperatures for onset and zero resistance of 95 K and 84 K, respectively. Although the X-ray diffraction measurement showed the film consists of an orthorhombic structure with the lattice constants a, b and c, respectively, of 3.883 Å, 3.830 Å and 11.70 Å, most of the surface layer was found by electron spectroscopy for chemical analysis (ESCA) to be significantly Er-deficient.
Photoluminescence Study of GaAs Grown Directly on Si Substrates
Authors: Enatsu Masao , Shimizu Masafumi , Mizuki Toshio , Sugawara Kazushi , Sakurai Takeshi
Published: November 2005

The photoluminescence (PL) spectra of heteroepitaxial GaAs layers grown on Si substrates by MOCVD and those of epitaxial GaAs films prepared by stripping off the Si substrates were observed at 77 K and 2 K in order to clarify the effect of internal stress in the GaAs layers. It was found that the shift of the PL peak position of the band-edge emission lines at these temperatures can be elucidated quantitatively by the strain due to the difference in the thermal expansion coefficients of GaAs and Si.
Magnetization Processes of an Agglomerate of Two Spheres with Nonvanishing Magnetocrystalline Anisotropy
Authors: Richter H. J. , Hempel K. A. , Pietsch R.
Published: November 2005

In this paper complete magnetization loops of an agglomerate of two identical single domain spheres are calculated. All configurations of the directions of the magnetically easy axes and of the applied field will be considered, if uniaxial magnetic anisotropy and dipole-dipole-interaction are taken into account. The spheres are assumed to be uniformly magnetized. It turns out that magnetostatic interactions in a single domain particle assembly play aless significant role even in materials exhibiting a not so strong magnetocrystalline anisotropy. For the case of predominant dipole-dipole-interaction the results of Jacobs and Bean (chain of spheres model) are confirmed.
Frequency Mixing of 50 GHz Microwave and 4.25 THz FIR Light by a Josephson Point Contact
Authors: Miki Yukinobu , Sakuma Eiichi
Published: November 2005

The harmonic mixing of 50 GHz microwave and 4.25 THz far-infrared (FIR) light, the highest order mixing ever reported in this frequency range, has been achieved using a Josephson point contact made of Nb. The conditions under which the mixing was performed are described. The conversion efficiency of the incident FIR light to the beat signal is evaluated and the performance limit of the Nb Josephson point contact is also discussed.
Preparation of YBa2Cu3O7-x Superconducting Thin Films by RF-Magnetron Sputtering
Authors: Aida Toshiyuki , Fukazawa Tokuumi , Takagi Kazumasa , Miyauchi Katsuki
Published: November 2005

Thin films of Y-Ba-Cu-O system have been prepared by rf-magnetron sputtering technique. The sputtered film was a multilayer composed of (Ba, Cu, O) and (Y, Cu, O). The films were crystallized by a high temperature chemical reaction between BaCuO2 and Y2Cu2O5 layers. Critical temperatures of YBa2Cu3O7-x
thin fims in this study were 80-85 K.
Space-Group Determination of La2CuO4-δ by Conventional and Convergent-Beam Electron Diffraction
Authors: Tanaka Michiyoshi , Tsuda Kenji , Yamada Kazuyoshi , Endoh Yasuo , Hidaka Yoshikazu , Oda Migaku , Suzuki Minoru , Murakami Toshiaki
Published: November 2005

The space group of La2CuO4-δ (δ≤0.02-0.03) was unambiguously determined to be Pccn by conventional and convergent-beam electron diffraction. It was found that all of as-grown, oxidized and deoxidized crystals belong to the same space group. The atomic positions do not appear to differ greatly from those given for (La1-x
Ba
x
)2CuO4-δ by Onoda et al. (Jpn. J. Appl. Phys. Lett. 26 (1987) L363).
A Stable Quasicrystal in Al-Cu-Fe System
Authors: Tsai An-Pang , Inoue Akihisa , Masumoto Tsuyoshi
Published: November 2005

A thermodynamically stable quasicrystalline single phase with an icosahedral structure was found to be formed at an atomic composition of Al65Cu20Fe15 in a fully annealed state as well as in a conventionally solidified state. The stable quasicrystal consisted of large grains with an average size of 0.2 mm after annealing for 48 h at 1118 K (0.98 Tm).
Bulk Nature of High-Tc Superconductivity in ErBa2Cu3O6+x
Authors: Mazaki Hiromasa , Ishida Takekazu
Published: November 2005

The magnetic response of ErBa2Cu3O6+x
has been studied in terms of complex susceptibility χ=χ'-iχ''. Our previous work suggested that the superconductivity of ErBa2Cu3O6+x
consists of bulk and weakly-coupled phases. We pulverized the pellet to depress the superconductive couplings in the specimen. The ac susceptibility data well reflect a bulk superconductive nature: χ' is insensitive to the field amplitude and χ'' does not show any change in the transition region, giving sound confirmation of our previous explanation.
Chemical Etching of High-Tc Superconducting Y-Ba-Cu-O Films in Phosphoric Acid Solution
Authors: Yoshizako Yuji , Tonouchi Masayoshi , Kobayashi Takeshi
Published: November 2005

Chemical etching properties of a high-Tc Y-Ba-Cu-O film with a phosphoric acid (H3PO4) solution were closely investigated. With an appropriate stirring, the etching developed in proportion to the time. The etching rate R was dependent on the dilution γ of H3PO4: R (µm/s)≃2γ for γ≤0.5, and otherwise it decreased superlinearly with increasing γ. A 2 µm wide Y-Ba-Cu-O line was fabricated using this technique with a positive-type photoresist such as AZ-1350J. Nosign of degradation of the superconductivity was found in the 50 µm wide etched lines. Rather, they showed an extreme enhancement of the onset temperature after this procedure.
MOCVD Growth of InP Using Red-Phosphorus and Hydrogen Plasma
Authors: Naitoh Masami , Umeno Masayoshi
Published: November 2005

InP epitaxial layers have been grown by metalorganic chemical vapor deposition using red-phosphorus and hydrogen plasma alternative to PH3 gas cylinder. The carrier concentration was 3.9×1016 cm-3 and the Hall mobility was 3650 cm2/V s at 300 K. Quadrupole mass spectrometer showed that the group V sources in this method were PH3 and phosphorus vapor.
Superconducting Transition in the YxEr1-xBa2Cu3O6+y System
Authors: Ishida Takekazu
Published: November 2005

The high-T
c superconductivity of the Y
x
Er1-x
Ba2Cu3O6+y
system has been investigated in terms of the resistive superconducting transition. The samples were simultaneously prepared under identical conditions to avoid ambiguity in the preparation history. The X-ray diffraction patterns showed that our samples have a single-phase orthorhombic structure. We observed a sharp superconducting transition of less than 0.95 K in width. T
c is almost independent of Y and Er concentrations.
Resistivity, Magnetization, Susceptibility and Critical Current Density of High-Tc Superconductor ErBa2Cu3O7-δ
Authors: Oota Akio , Kiyoshima Yoshio , Shimono Akira , Koyama Kuniyuki , Kamegashira Naoki , Noguchi Seiichiro
Published: November 2005

The ErBa2Cu3O7-δ sample which is of a single phase of the orthorhombic YBa2Cu3O7-δ structure has shown the value of T
c=90.0±0.7 K and the Meissner flux expulsion up to 50% at 79 K. The critical current density was 350 A/cm2 at zero magnetic field, while it decreased rapidly with increasing field. The magnetic susceptibility in normal state is explained by the Curie-Weiss law with the effective moment µeff=9 µB which is in good agreement with the one for the free ion of Er.
Studies on Anisotropic Upper Critical Fields of HoBa2Cu3O7-δ and ErBa2Cu3O7-δ Using Preferentially Oriented Pellets
Authors: Takita Kôki , Akinaga Hiroyuki , Katoh Hideo , Masuda Kohzoh
Published: November 2005

Anisotropic behaviors of the upper critical fields H
c2 studied in as-sintered disks of HoBa2Cu3O7-δ and ErBa2Cu3O7-δ are described. Highly oriented samples with c-axis perpendicular to the disk plane, which are characterized by X-ray diffraction analysis, show anisotropic behavior of H
c2 for midpoints and almost isotropic behavior for the offset field. For HoBa2Cu3O7-δ, the slopes (-dH
c2/dT) for midpoints are 5.2 T/K and 2.5 T/K for the magnetic field parallel and perpendicular to the disk plane, respectively, and are 3.9 T/K and 1.9 T/K for ErBa2Cu3O7-δ. An analysis based on a simplified model of preferentially oriented disk of a quasi-two-dimensional anisotropic superconductor suggests that the anisotropy factor ε between the c-axis and the a-b plane is about 0.2 for both materials.
A New-Type 1.5∼1.6 µm GaInAsP/InP BIG-DBR Laser by an Island-Type Mesa Process
Authors: Choi In-Hoon , Komori Kazuhiro , Arai Shigehisa , Suematsu Yasuharu , Lee Keun-Sam , Pang Mu-Ting
Published: November 2005

A new-type BIG-DBR laser was fabricated by introducing an island-type mesa process to improve the fabrication yield of the smooth joint portion between an active and an external waveguide. Improved device properties such as a threshold current of 35 mA, a light output power of 12.4 mW and a differential quantum efficiency of 22.1 % /facet were obtained under the CW operation for this laser with an active region length of 400 µm and a stripe width of 3 µm. The temperature range for a fixed single-mode operation exceeded 70 degrees around room temperature.
Intermixing Process of InGaAs/InP MQW Grown by Metalorganic Molecular Beam Epitaxy at Thermal Annealing
Authors: Nakashima Kiichi , Kawaguchi Yoshihiro , Kawamura Yuichi , Asahi Hajime , Imamura Yoshihiro
Published: November 2005

The intermixing process of InGaAs/InP multiple-quantum-well(MQW) structure by thermal annealing at 500-700°C is investigated. Optical measurement appears to show that the MQW structure is unstable in the annealing above 700°C. SIMS and X-ray analysis, however, reveal that the MQW structure remains basically intact and that this intermixing process is mainly attributable to a minor diffusion of P atoms inducing a lattice-mismatched layer. The pronounced optical peak shifts can be roughly explained on the basis of this minor diffusion process.
Misfit and Threading Dislocations in GaAs Layers Grown on Si Substrates by MOCVD
Authors: Ishida Koichi , Akiyama Masahiro , Nishi Seiji
Published: November 2005

The misfit dislocations at GaAs/Si interface and threading dislocations in the GaAs layers grown on Si by MOCVD have been studied by transmission electron microscopy. The misfit dislocation is a pure edge dislocation with Burgers vector of 1/2 a <110> parallel to the interface. The threading dislocations are either the end portions of the misfit dislocations or dislocations with Burgers vector of 1/2 a <101> inclined to the surface. Most of the threading dislocations are not revealed as conventional large etch pits by molten KOH etching. Therefore, the molten KOH etching underestimates the dislocation density in the GaAs layer by about three orders of magnitude.
Effect of Plasma Treatment on Photovoltaic Properties in Copper Phthalocyanine
Authors: Miyata Seizo , Park Yun Heum , Soeda Yoshihiro , Itoh Rie , Tasaka Shigeru
Published: November 2005

The power-conversion efficiency of ITO (indium tin oxide)/CuPc (copper phthalocyanine)/Al cells increased to as high as 0.8 percent when a CuPc evaported film was treated by Ar-plasma. The results of the ESCA spectrum and the absorption spectrum suggested that the film surface changed to a structure containing oxygen which is introduced after contact with air.
Polarizing Microscopic Observation of the Superconducting Eu1Ba2Cu3Oy Crystals
Authors: Semba Kouichi , Suzuki Hiroyuki , Katsui Akinori , Hidaka Yoshikazu , Hikita Makoto , Tsurumi Shigeyuki
Published: November 2005

The orthorhombic high-T
c Eu1Ba2Cu3O
y
crystals are investigated optically by the polarizing microscope. The crystals are optically anisotropic in the a-b plane, and the phase difference between the advanced- and the retarded-phase axis is 30±3 degrees along the a- and b-axes. According to the reflection formula for metals, the anisotropic conductivity between these two directions is analyzed. The anisotropy of a factor of about 2 is obtained.
Preparation and Physical Properties of PrBa2Cu3Oy
Authors: Okai Bin , Takahashi Koh , Nozaki Hiroshi , Saeki Masanobu , Kosuge Michikazu , Ohta Masatsune
Published: November 2005

A new compound, PrBa2Cu3O
y
, which is isomorphic with YBa2Cu3O
y
, was prepared as single phase. With specimens quenched from 920°C, the oxygen content y was 6.8 ± 0.1 and the ratio of Pr3+ to Pr4+ was 0.4:0.6. With furnace-cooled specimens, the value of y was 7.1 ± 0.1 and the ratio became 0.1:0.9. The average valence of Cu ions was 2.0 ± 0.1 for the former and 2.1 ± 0.1 for the latter. Specimens handled both ways were nonmetallic and nonsuperconducting down to 4.2 K.
Vibrational Excitations of Methane Monolayer Physisorbed on Ag(111) Surfaces
Authors: Sakurai Makoto , Okano Tatsuo , Tuzi Yutaka
Published: November 2005

Vibrational spectra of a CH4 monolayer were studied by high-resolution electron energy loss spectroscopy. Monolayer of CH4 was physisorbed on a Ag(111) surface at 40 K. The dependence of vibrational excitation cross section on the incident electron energy and scattering geometry was studied. Excitation of the v
4 mode was mainly excited by dipole scattering, while the v
2 mode was excited via impact scattering. The combinational mode was observed at the incident electron energies of 6-10 eV. The effect of negative-ion resonance is discussed from the experimental results.
MOCVD Preparation of Polycrystalline ZnS Films with Pronounced Columnar Grains
Authors: Shibata Tomohiro , Hirabayashi Katsuhiko , Kozawaguchi Haruki , Tsujiyama Bunjiro
Published: November 2005

ZnS films having good crystallinity are grown on glass by MOCVD using dimethylzinc and diethylsulphide. These films consist of very pronounced columnar grains that extend from the bottom to the top of the film. The crystal structure of these films is hexagonal.
Thin film electroluminescent devices are fabricated using these films and their characteristics are measured.
Superconductivity in Ba2(1-x)Sr2xYCu3O7-y
Authors: Ono Akira , Tanaka Takaho , Nozaki Hiroshi , Ishizawa Yoshio
Published: November 2005

We report X-ray and chemical properties, phase transition, magnetic susceptibility and superconducting transition temperature of Ba2(1-x)Sr2x
YCu3O7-y
. Structural instability was detected for sample with x≥0.6. Phase transition occurs at oxygen number of 6.6. Anomalies in magnetization curves at 4.2 K were detected. The T
c decreases linearly from 92 to 80 K with an increase of x. Strontium and oxygen contents are parameters correlated with the depression of T
c.
Electron Diffraction and Microscope Study of Ba-Nd-Cu-O Superconducting Oxides and Related Compounds
Authors: Matsui Yoshio , Takekawa Shunji , Iyi Nobuo
Published: November 2005

Four compounds within a range of solid solution Ba2-x
Nd1+x
Cu3O
y
(where x ranges from 0 to 0.8) are examined by transmission electron microscopy. Ba2NdCu3O
y
, with T
c= 83 K, has an ortho rhombic structure with twinned microstructure, similar to that of Ba2YCu3O
y
with T
c= 90 K. Ba1.8Nd1.2Cu3O
y
, with T
c= 45 K, and Ba1.5Nd1.5Cu3O
y
(nonsuperconductor) are both tetragonal, but the latter has a domain structure where the c axes of neighboring domains are perpendicular to each other. Ba1.2Nd1.8Cu3O
y
(nonsuperconductor) has a superstructure with A
s=2a, B
s=b and C
s=2c. Two possible models of the superstructure are proposed.
Highly Sensitive Spectrometer with 0.78 µm AlGaAs Diode Lasers
Authors: Nakagawa Ken'ichi , Shimizu Tadao
Published: November 2005

A reasonably high sensitivity of 3×10-8/cm has been achieved in the near IR spectrometer with AlGaAs diode lasers. Source modulation and Stark modulation techniques are helpful to improve the sensitivity. A successful application to the observation of very weak transitions to the highly excited vibrational states (υN-H=4) of NH3 is demonstrated. All Stark components are resolved and the rotation-vibration transitions are definitely assigned.
Field-Effect Induced Sinusoidal Conductivity Variation of NbN Granular Thin Film
Authors: Yoshikawa Nobuyuki , Akeyoshi Tomoyuki , Sugahara Masanori
Published: November 2005

Sinusoidal conductivity variation is observed in highly resistive granular NbN thin films when an external electric field is applied perpendicular to the film surface at low temperatures. The electric charge necessary to make 1 cycle of conductivity variation is estimated to be about electron pair charge 2e.
A Low-Temperature Electron Microscopy and Electron Diffraction Study of La1.84Sr0.16CuO4
Authors: Onozuka Takashi , Omori Mamoru , Hirabayashi Makoto , Syono Yasuhiko
Published: November 2005

A high-T
c superconducting compound, La1.84Sr0.16CuO4, has been investigated by electron microscopy and electron diffraction in the range from 10 K to ambient temperature. The tetragonal K2NiF4-type structure undergoes an orthorhombic distortion below about 130 K. In the low-temperature phase, extra diffraction spots and twin lamellae are observed reversibly on cooling and heating in situ. Based on the observed results, a plausible structure model with orthorhombic distortion is proposed.
Ruby-Laser Scattering Diagnostics of a Supersonic Plasma Flow for Low-Pressure Plasma Spraying
Authors: Hidaka Ryouta , Ooki Tsutomu , Takeda Kouichi , Kondo Katsuyuki , Kanda Hiroshi , Uchino Kiichiro , Matsuda Yoshinobu , Muraoka Katsunori , Akazaki Masanori
Published: November 2005

Truly reliable measurements of electron temperature and density in a plasma flow for low-pressure plasma spraying (LPPS) were performed for the first time, using incoherent Thomson scattering of ruby-laser light. The results indicate the characteristic feature of a supersonic nozzle flow, namely, successive appearance of oblique shock-wave heating (∼1 eV) and compression (4×1021 m-3), and subsequent cooling (∼0.2 eV) and rarefaction (1×1021 m-3).
The Growth of Single Domain GaAs Films on Double Domain Si(001) Substrates by Molecular Beam Epitaxy
Authors: Kawanami Hitoshi , Hatayama Akiteru , Nagai Kiyoko , Hayashi Yutaka
Published: November 2005

Single domain GaAs layers were successfully grown on double domain Si(001) substrates by molecular beam epitaxy (MBE). During the growth, reflection high energy electron diffraction (RHEED) patterns of GaAs films grown on the Si substrates were monitored in situ. They changed gradually from initial spotty unreconstructed patterns to As stabilized (001)2×4 patterns. The morphologies of as grown surfaces and molten KOH etched surfaces of the films were observed by Nomarski optical microscope and also indicate that the films were single domain.
Energy Beam Irradiation of High-Tc Superconductors Y1Ba2Cu3O7-y and Ho1Ba2Cu3O7-y
Authors: Murakami Kouichi , Eryu Osamu , Takita Kôki , Masuda Kohzoh
Published: November 2005

We have investigated energy beam irradiation of high-T
c superconductors which were treated in various ways. It is found for the first time that infrared-light irradiation and cw-laser irradiation for short periods are useful to get an orthorhombic phase with T
c of about 90 K at local regions from a tetragonal phase or a quenched amorphous-like phase, including mixed tetragonal and orthorhombic phases. It is likely that an amorphous phase produced by ion implantation of 400 keV O+ up to a dose of 1×1017/cm2 is transformed to the superconducting orthorhombic phase by thermal annealing at 900 and 950°C.
Antiferromagnetic Ordering in GdBa2Cu3Oy Superconductor
Authors: Nakamura Fumihiko , Tominaga Akira , Narahara Yoshimasa
Published: November 2005

Dc susceptibilities of GdBa2Cu3O
y
are measured. Temperature dependence of the susceptibilities of the normal states obeys the Curie-Weiss law, and the antiferromagnetic ordering is expected from the Weiss temperature. Below the superconducting transition temperatures, the susceptibilities decrease due to the Meissner effect and increase due to paramagnetic behavior of gadolinium ions. At 2.25 K the peak related to the antiferromagnetic ordering is observed. Above the Néel temperature the susceptibility has a hysteresis when the applied field is 100 Oe.
Pulsed Power Generation from an Inductive Energy Storage System by Fuses and a Plasma Erosion Opening Switch
Authors: Akiyama Hidenori , Majima Takashi , Fujita Kouichi , Maeda Sadao
Published: November 2005

The pulsed power generation from the inductive energy storage system, which is extremely compact and light, is investigated by the two-staged opening switches of fuses and a plasma erosion opening switch. The current rise time decreases from about 1 µs to about 200 ns by the fuses, and then to about 100 ns by the plasma erosion opening switch.
Superconducting Transition of GdBa2Cu3O7-x
Authors: Mazaki Hiromasa , Takano Mikio , Kanno Ryoji , Takeda Yasuo
Published: November 2005

The superconducting transition of GdBa2Cu3O7-x
has been studied in terms of complex susceptibility and ac resistance. The results suggest the superconducting transition of a disk sample takes place through the concurrence of the bulk and coupled phases. The ac-resistive measurement of a disk sample as well as the complex-susceptibility measurement of a powdered sample support the above results. Discussion was made with the aid of the weak-link loop model.
GaInAsP/InP Single Quantum-Well Lasers by OMVPE
Authors: Miyamoto Yasuyuki , Cao Ming , Furuya Kazuhito , Suematsu Yasuharu
Published: November 2005

Lasing in GaInAsP/InP SCH single-quantum-well lasers is reported for the first time and confirmed by the oscillation wavelength. Threshold current densities were 230 A/cm2 and 11 kA/cm2 for CW operation at 77 K and pulsed operation at room temperature, respectively. It was experimentally found important to make the band-gap energy difference between quantum-well and optical confinement layers larger than 0.23 eV in order to confine carriers in the quantum-well layers.
Spectral Shift of Photoluminescence of Highly Doped GaAs Epitaxial Layers Grown by MOCVD
Authors: Okamoto Kotaro , Kurihara Nobuaki
Published: November 2005

The photoluminescence spectra of Se-doped and Si-doped GaAs epitaxial layers grown by metalorganic chemical vapor deposition (MOCVD) were measured and compared. The spectral shift of Se-doped samples changes only with the carrier concentration, which can be explained by the Moss-Burstein shift, while that of Si-doped samples depends not only on the carrier concentration but also on growth rates and V/III mole fractions. It became apparent from X-ray diffraction that the lattice constant began to decrease in highly Si-doped layers and that the anomalous spectral shifts are caused by the lattice compression originating from a high density of [SiGa-SiAs] pairs incorporated in highly Si-doped layers.
Synergistic Enhancement of Direct Synchrotron Radiation Etching of a Resist by a Low-Energy Oxygen Beam
Authors: Murakami Hiroshi , Ichimura Shingo , Shimizu Hazime , Kudo Isao , Atoda Nobufumi
Published: November 2005

The effect of the simultaneous irradiation of a low-energy oxygen ion beam with synchrotron radiation (SR) was investigated. The purpose was the enhancement of the direct resist etching by SR. Although the removal by sputtering of the resist was observed due to the wide energy width of the ion beam used, it was confirmed that the net SR etching, which was estimated after subtraction of the sputtering contribution, increased about two times. Possibilities for the enhancement of this “synergistic effect” induced by low-energy ion beam bombardment to improve the direct SR etching and make it more practical are also discussed.
Giant Electroclinic Effect in Chiral Smectic A Phase of Ferroelectric Liquid Crystals
Authors: Nishiyama Shin-ichi , Ouchi Yukio , Takezoe Hideo , Fukuda Atsuo
Published: November 2005

A giant electroclinic effect was observed in smectic A (SA) phases of various ferroelectric liquid crystals with spontaneous polarizations as large as several hundred µC/m2. An induced tilt angle increased linearly with an electric field, E, and tended to saturate toward 16° . The induced tilt angle of a few degrees was observable even at a temperature 20° above the SA-SC
* transition. It was confirmed using several compounds that the induced tilt angle is proportional to the spontaneous polarization in SC
*. The response time is less than 1 µs and, when normalized by the induced tilt angle, linearly depends on E, i.e., τ'/θ0∝E.
Incipient Twinning in Ba2YCu3O7-x Crystals
Authors: Iijima Sumio , Ichihashi Toshinari , Kubo Yoshimi , Tabuchi Junji
Published: November 2005

Twinning in Ba2YCu3O7-x
crystals prepared by the standard sintering method was examined by electron optical methods. Under electron beam irradiation in a vacuum in an electron microscope, an orthorhombic crystal transformed irreversibly to a tetragonal form. Prior to the complete transformation, an “incipient” twinning state was observed. The incipient state is considered in terms of domain formation of a tetragonal form.
Phonon Raman Scattering in Orthorhombic and Tetragonal YBa2Cu3O7-δ
Authors: Nakashima Shin-ichi , Hangyo Masanori , Mizoguchi Kohji , Fujii Akihito , Mitsuishi Akiyoshi , Yotsuya Tsutomu
Published: November 2005

Raman scattering spectra of orthorhombic and tetragonal YBa2Cu3O7-δ have been measured. It is found that the Raman band associated with oxygen vibrations in the tetragonal phase is shifted to the lower frequency side with respect to the corresponding band in the orthorhombic phase. Seven Raman bands out of the ten theoretically predicted are found in the orthorhombic phase. No remarkable temperature dependence was observed for the phonon modes above 100 cm-1.
Frequency-Dependent Conductivity in Polyaniline
Authors: Hayashi Takafumi , Hirai Yoshinori , Tanaka Hajime , Nishi Toshio
Published: November 2005

Frequency(f) and temperature(T) dependence of electrical conductivity σ(f, T) and optical spectrum in polyaniline are presented. The behavior of σ(f, T) at low protonation levels is the same as the lightly doped polypyrrole. These results can be described by the slightly modified Kivelson model, that is, the interpolaron hopping between the polaron and bipolaron. The behavior of σ(f, T) in highly protonated polyaniline is the same as in disordered semiconductors.
Structure and Electronic Properties of Polyaniline
Authors: Hayashi Takafumi , Hirai Yoshinori , Tanaka Hajime , Nishi Toshio
Published: November 2005

Degree of protonation and oxidation dependence of the spin-lattice relaxation time T
1 (1H-NMR), 13C-NMR spectrum, FT-IR spectrum for polyaniline are presented. It is concluded that benzoid rings in the chain are transformed into quinoid rings by oxidation, and in oxidized polyaniline the degree of localization of electrons is dominated by the degree of protonation.
Fluorescence EXAFS Study of AlGaAs Doped with Se Donor Impurities
Authors: Kitano Tomohisa , Mizuta Masashi
Published: November 2005

We performed extended X-ray absorption fine structure measurements on Al0.38Ga0.62As:Se in order to investigate the lattice relaxation accompanying the existence of the deep level. The local structure of Se donor impurities was observed by monitoring the Se Kαfluorescence yield. A small glancing angle arrangement was applied to suppress the effects of both Ga and As Kαfluorescence X-rays. The nearest-neighbor distances around Se were not influenced by the existence of the deep level.
Atomic Structure of Ordered InGaP Crystals Grown on (001)GaAs Substrates by Metalorganic Chemical Vapor Deposition
Authors: Ueda Osamu , Takikawa Masahiko , Komeno Junji , Umebu Itsuo
Published: November 2005

InGaP crystals grown on (001)GaAs substrates by metalorganic chemical vapor deposition are structurally evaluated by transmission electron microscopy. High-resolution electron microscopy observation and electron diffraction analysis of both the (110) and the (11̄0) cross-section specimens strongly suggest that ordering of column III atoms on only two sets of the (111) planes with doubling in periodicity of (111) layers, i.e., In/Ga/In/Ga/In/Ga. . ., is occurring in the crystal. The ordering of the crystal is not perfect, and the ordered regions are assumed to be plate-like microdomains.
Photon-Induced Hopping in High-Tc Superconductors
Authors: Nagasaka Keigo , Sato Masayuki , Ishii Chikara
Published: November 2005

Measurements of far infrared absorption coefficients have been performed in the low frequency range from 20 to 300 cm-1 for the high-T
c superconductors La2-x
Sr
x
CuO4 and YBa2Cu3O7-y
. It is shown that the absorption of La2-x
Sr
x
CuO4 increases with frequency, ω, of radiation according to the power law both below (4.2 K) and above (70 K) the transition temperature, and similar behavior of the absorption of YBa2Cu3O7-y
is observed at 4.2 K. It is suggested that such behavior of absorption may be ascribable to the photon-induced hopping of topological excitations in these materials.
Critical Field Anisotropy of a Single Crystal GdBa2Cu3Ox and HoBa2Cu3Ox
Authors: Iye Yasuhiro , Tamegai Tsuyoshi , Takeya Hiroyuki , Takei Humihiko
Published: November 2005

A study of anisotropic critical field has been carried out on single crystal samples of GdBa2Cu3O
x
and HoBa2Cu3O
x
. The angular dependence of the upper critical field can be fitted to the anisotropic Ginzburg-Landau model. The anisotropy ratio H
c2
⊥/H
c2
// depends somewhat on the definition of H
c2 and is also temperature dependent, but it generally falls between 3 and 7. The superconducting properties of GdBa2Cu3O
x
and HoBa2Cu3O
x
are almost identical with that of YBa2Cu3O
x
which we reported earlier, except for small differences in T
c.
First Observation of an Antiferromagnetic Phase in the Y1Ba2Cu3Ox System
Authors: Nishida Nobuhiko , Miyatake Hideaki , Shimada Daisuke , Okuma Satoshi , Ishikawa Masayasu , Takabatake Toshiro , Nakazawa Yasuhiro , Kuno Yoshitaka , Keitel Rolf , Brewer Jess H. , Riseman Tanya M. , Williams David Ll. , Watanabe Yasushi , Yamazaki Toshimitsu , Nishiyama Kusuo , Nagamine Kanetada , Ansaldo Eduardo J. , Torikai Eiko
Published: November 2005

The magnetic properties of four different phases of the YBa2Cu3O
x
system, including the famous 90 K superconductor, have been probed by the positive muon spin relaxation method (µ+SR). The oxygen-deficient tetragonal insulating phase (x∼6.2) was found to be magnetically ordered, thus most likely antiferromagnetic, near room temperature.
Dependence of Magnetic Susceptibility of Ba2YCu3O7-x on the Oxygen Defect Concentration
Authors: Takabatake Toshiro , Ishikawa Masayasu , Sugano Tadashi
Published: November 2005

We report the results of magnetic susceptibility measurements on Ba2YCu3O7-x
with various oxygen content (0.1≤x≤0.82) in the temperature range between 78 and 500 K. No sign of long-range magnetic order was observed for any oxygen content. With increasing oxygen defect concentration, x, from 0.1 to 0.82, the Pauli susceptibility gradually decreases from 7×10-4 emu/mol f.u. to half, while a Curie-Weiss-like contribution increases significantly. We ascribe this contribution to the effect of electron localization caused by the random distribution of oxygen defects.
Low-Temperature Growth of Transparent and Conducting Tin Oxide Film by Photo-Chemical Vapor Deposition
Authors: Tabuchi Toshiya , Yamagishi Koji , Tarui Yasuo
Published: November 2005

For the first time, photo-CVD of transparent and conducting SnO2 films has been achieved under irradiation by a low-pressure Hg lamp. It was confirmed that both resonance lines (254 nm, 185 nm) are effective for the activation of CVD-sources (O2, SnCl4, SbCl5). The structural, electrical and optical properties of undoped and Sb-doped SnO2 films prepared by the photo-CVD method were evaluated. Resistivity as low as 5.48×10-3 ohm·cm with high optical transmission (80%) was obtained in Sb-doped SnO2 films (80 nm in thickness).
Crystal Structures and Electrical Properties of L1.5Ba1.5Cu3Oy(L=La, Pr, Nd, Sm, Eu, Gd, Y and Yb)
Authors: Tsurumi Shigeyuki , Iwata Tsunekazu , Tajima Yukimichi , Hikita Makoto
Published: November 2005

The L1.5Ba1.5Cu3O
y
compounds for L=lanthanides have been investigated by X-ray powder diffraction analysis and electrical resistivity measurement. A single L1.5Ba1.5Cu3O
y
phase has been firstly obtained in the samples for L=Nd, Sm and Eu as well as La and Pr exhibiting the semiconductor-like behavior of resistivity down to about 10 K. This single phase has not been obtained in the samples for L=Gd, Y and Yb having the LBa2Cu3O
y
and L2BaCuO
y
phases and exhibiting the superconductivity. The stability of the L1.5Ba1.5Cu3O
y
single phase is found to depend on the L3+ ion radius and sintering condition.
Antiphase Domain Structure in Gd75Sc25 Single-Crystal Alloys
Authors: Ito Takashi , Takeuchi Jun , Mizuno Kaoru , Ito Kazuyoshi , Oka Masahiro , Beaudry Bernard J.
Published: November 2005

Magnetization, low field ac susceptibility, electrical resistivity, ultrasonic attenuation and specific heat have been measured for Gd75Sc25 single crystals. Low field ac susceptibility curves for the c-axis sample exhibit a sharp peak at the highest ordering temperature T
c (= 187 K) and a drop between T
c and T
2 (= 126 K), which suggest the existence of an antiphase domain ferrimagnetic structure. A similar conclusion has been reached from the results of electrical resistivity, elastic property and specific heat measurements.
Displacement Waves in La2CuO4-δ and La1.85Sr0.15CuO4-δ
Authors: Kajitani Tsuyoshi , Onozuka Takashi , Yamaguchi Yasuo , Hirabayashi Makoto , Syono Yasuhiko
Published: November 2005

Structural investigation of orthorhombic La2CuO4-δ and La1.85Sr0.15CuO4-δ was carried out by means of X-ray and neutron diffraction on the basis of the space group Cmmm. The periodic expansion/contraction type distortion of CuO6 octahedra was found in both orthorhombic compounds. The distortion is nearly one-dimensional in La2CuO4-δ but is two-dimensional in La1.85Sr0.15CuO4-δ. The existence of a charge-density wave, CDW, with a wave vector q
CDW=(0 0 c
*) is highly possible in the structures.
Upper Critical Field Measurements on a Single Crystal YBa2Cu3Ox up to 38 T
Authors: Sakakibara Toshiro , Goto Tsuneaki , Iye Yasuhiro , Miura Noboru , Takeya Hiroyuki , Takei Humihiko
Published: November 2005

The anisotropic upper critical fields of a single crystal of orthorhombic YBa2Cu3O
x
have been measured in pulsed high magnetic fields up to 38 T. The critical fields B
c2 defined by the onset of the resistance for parallel and perpendicular directions to the c-axis show a linear temperature dependence above 10 T with the slopes |dB
c2
///dT| = 1.1 T/K and |dB
c2
⊥/dT| = 3.9 T/K, whereas the B
c2 vs T curves show positive curvatures in the lower fields. At liquid nitrogen temperature, the zero resistance state cannot be destroyed by the field of 38 T and B
c2
⊥ is estimated as 45 T.
High-Quality LB Films of Artificial Dialkyl Lipid
Authors: Onoue Yoichi , Moriizumi Toyosaka , Okahata Yoshio , Ariga Katsuhiko
Published: November 2005

LB films (4 monolayers) of artificial dialkyl lipid were deposited over Au evaporated films on glass substrates. The film quality was examined using the Cu decoration method and optical polarization microscopy. The defect density of the lipid film was much less than that of a monoalkyl film. Moreover, the defect density was so decreased after thermal annealing and rinsing in an alcohol solution that LB films which were almost defect-free were obtained. Microscopic observation revealed a snowflake crystalline pattern after the annealing and rinsing treatments.
Formation of Ferromagnetic MnAl Layers by Ion Beam Mixing
Authors: Kido Yoshiaki , Suzuki Nobuaki , Kawamoto Junichi
Published: November 2005

It is first demonstrated that the ferromagnetic MnAl layers are formed directly by ion beam induced mixing with 400 keV Xe+ ions. Their magnetic properties strongly depend on the ion dose and the substrate temperature during ion irradiation. A characteristic spectral line originating from the metastable τ phase with ferromagnetism is observed in the X-ray diffraction measurement. The results obtained lead to the conclusion that the dynamical collision cascades assisted by the enhanced diffusion are the decisive factors forming the ferromagnetic MnAl layers.
Characterization of Diamond Particles and Films Formed by Plasma-Assisted Chemical Vapour Deposition Using High-Voltage Electron Microscopy
Authors: Kawarada Hiroshi , Mar King Sheng , Suzuki Jun-ichi , Ito Toshimichi , Mori Hirotaro , Fujita Hiroshi , Hiraki Akio
Published: November 2005

The internal and interfacial structures of diamond particles and films on Si substrates formed by plasma-assisted chemical vapour deposition have been investigated by high-voltage transmission electron microscopy. The feature of line defects–micro-twin lamellae or stacking faults–in a diamond particle indicates the concentric crystal growth originated from one nucleus. The particles are observed to be in direct contact with the Si substrate around the nucleation site within the resolution limit. The particles are stacked up to form a diamond film.
Superconductivity by Fermion Pairing in Real Space and the Physical Properties of High-TcOxide Superconductors
Authors: Takeno Shozo , Kisoda Kenji
Published: November 2005

The assumption of fermion pairing in real space, its modelling by a pseudo-spin Hamiltonian, and use of a mean-field argument lead to the anisotropic-effective-mass Ginzburg-Landau equation applicable for allT<Tc. The superconducting properties obtained by such a tight-binding model are somewhat different from those of the BCS theory. Namely, it yields: (1) very short coherence length, (2) strong anisotropy, (3) large Ginzburg-Landau parameter κ, (4) large critical magnetic field, and so on, in addition to highTc. This accounts for the characteristic superconducting properties of the Y-Ba-Cu-O system.
Anisotropic Properties of Superconducting (La1-xSrx)2 CuO4 Single-Crystal Thin Films
Authors: Suzuki Minoru , Enomoto Youichi , Moriwaki Kazuyuki , Murakami Toshiaki
Published: November 2005

Anisotropies of resistivity and the upper critical magnetic field in superconducting (La1-x
SF
x
)2 CuO4 single-crystal thin films are observed to be 20-30 and 5.3, respectively. It is found that the temperature dependence of resistivity along the c-axis is strongly affected by defects, while that along the Cu-O plane is much less affected. This causes the variation in the anisotropy factor of resistivity. The coherence length in the c-axis direction is estimated to be 0.71 nm. The results indicate that this material is very close to a two-dimensional superconductor or a superconductor in the crossover region.
Low Temperature Specific Heat and Electrical Resistivity in Orthorhombic YBa2Cu3O6.8 and Tetragonal YBa2Cu3O6.0
Authors: Matsushita Akiyuki , Oguchi Tamio , Kimura Kazuhiro , Matsumoto Takehiko , Hatano Takeshi , Ogawa Keiichi , Takayanagi Shigeru
Published: November 2005

The low temperature specific heat and electrical resistivity of YBa2Cu3O6.8 and YBa2Cu3O6.0 have been measured. The specific heat data were taken at a temperature range from 2 K to 40 K. Abnormal upturns at the lower temperature end and a large electron contribution were observed in the C/T vs T
2 curve. The resistivity ρ was measured from 20 K to 270 K for YBa2Cu3O6.0. A strong current density dependence was observed. Log ρ measured at low current density was found to show T
-1/3 dependence below 170 K.