著者

Asaka Koji Kato Ryoei Miyazawa Kun'ichi Kizuka Tokushi

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.89, no.7, pp.071912, 2006-08

被引用文献数

32

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The authors demonstrated the mechanics of materials for crystalline whiskers composed of C60 molecules; compressive deformation of the whiskers was observed by in situ transmission electron microscopy with simultaneous force measurement by means of an optical cantilever method, as used in atomic force microscopy. In response to compression along the long axis, the whiskers bent first elastically, then buckled. A whisker with 160 nm diameter fractured brittlely at a strain of 0.08. According to Euler's formula, Young's modulus of the whisker was estimated to be 32–54 GPa, which is 160%–650% of that of C60 bulk crystals.

著者

Umeda T. Okonogi K. Ohyu K. Tsukada S. Hamada K. Fujieda S. Mochizuki Y.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.88, pp.253504, 2006-06

被引用文献数

25 18

---

The variable retention time phenomenon has recently been highlighted as an important issue in dynamic random access memory (DRAM) technology. Based on electrically detected magnetic resonance and simulation studies, we suggest that a single Si vacancy-oxygen complex defect is responsible for this phenomenon, when the defect is embedded in the near surface drain-gate boundary of a DRAM cell.

著者

Paul G. K. Nawa Y. Sato H. Sakurai T. Akimoto K.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.88, no.14, pp.141901, 2006-04

被引用文献数

86 41

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Hole traps in p-type Cu2O were studied by means of deep level transient spectroscopy in the heterostructure of p-Cu2O/i-ZnO/n-ZnO. In addition to the trap level at about 0.45 eV from the valance band edge, which is already reported as being due to Cu vacancy, we found a new trap level at about 0.25 eV. The new trap is tentatively assigned as Cu-di-vacancy from the trap concentration dependence on oxygen flow rate and substrate temperature.

著者

Kita Eiji Tsukuhara Naoki Sato Hidenori Ota Keishin Yangaihara Hideto Tanimoto Hisanori Ikeda Naoshi

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.88, pp.152501, 2006-04

被引用文献数

22 19

---

We prepared high-purity oxygen-free and single-phase Ni nanocrystals using the gas condensation and deposition method in order to examine the random anisotropy model (RAM). The grain size of an as-prepared sample was estimated to be 8–10 nm. Thermal annealing increased grain sizes (D) up to 22 nm. Clear D6 dependence of the coercive force on a grain size smaller than 13 nm was obtained for samples prepared on both plastic and KBr single-crystal substrates. For larger grain sizes, Hc decreased with D–1 and these results clearly conform to the RAM in single-element nanocrystal systems. A local anisotropy constant was estimated from the slope of the D6 relation and the peak of Hc at D=13 nm.

著者

Asaka Koji Kato Ryoei Maezono Yoshinari Yoshizaki Ryozo Miyazawa Kun'ichi Kizuka Tokushi

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.88, no.5, pp.051914, 2006-02

被引用文献数

19

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Filaments composed of multilayered carbon hollow capsules less than 10 nm in diameter have been synthesized from crystalline whiskers of fullerene C60 of submicrometer in diameter by preliminary heating at 1373 K and successive impression of current. The structural, electrical and optical properties of the filaments were studied by in situ transmission electron microscopy combined with the functions of scanning probe microscopy. We found that the filaments easily emit visible light at a maximum wavelength of 700-730 nm by the application of a few volts.

著者

Boero Mauro Oshiyama Atsushi Silvestrelli Pier Luigi Murakami Kouichi

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.86, no.20, pp.201910, 2005-05

被引用文献数

17 18

---

Recent experiments have shown that pure Si structures in a matrix of SiO2 can be formed by electron excitation techniques, with appealing applications in nanotechnology. Our ab initio simulations provide an insight into the underlying mechanism, showing that electron excitations weaken Si–O bonds in SiO2, dislodge O atoms and allow Si dangling bonds to reconstruct in stable Si–Si structures below the melting temperature. Differences in diffusivity of O (fast) and Si (slow) are shown to play a decisive role in the process.

著者

Fukata N. Oshima T. Murakami K. Kizuka T. Tsurui T. Ito S.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.86, no.21, pp.213112, 2005-05

被引用文献数

78 50

---

A gradual downshift and asymmetric broadening of the Si optical phonon peak were observed by Raman scattering measurements of continuously thermally oxidized silicon nanowires (SiNWs) synthesized by laser ablation. This downshift and broadening can be interpreted by the phonon confinement effect. Further thermal oxidation produced a reverse change; namely, an upshift of the optical phonon peak. This is considered to be due to compressive stress since this stress was relieved by removing the oxide layers formed around the SiNW cores, resulting in a downshift of the optical phonon peak.

著者

Boero Mauro Oshiyama Atsushi Silvestrelli Pier Luigi Murakami Kouichi

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.86, pp.201910, 2005-05

被引用文献数

17

---

Recent experiments have shown that pure Si structures in a matrix of SiO2 can be formed by electron excitation techniques, with appealing applications in nanotechnology. Our ab initio simulations provide an insight into the underlying mechanism, showing that electron excitations weaken Si–O bonds in SiO2, dislodge O atoms and allow Si dangling bonds to reconstruct in stable Si–Si structures below the melting temperature. Differences in diffusivity of O (fast) and Si (slow) are shown to play a decisive role in the process.

著者

Makimura Tetsuya Miyamoto Hisao Kenmotsu Youichi Murakami Kouichi Niino Hiroyuki

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.86, no.10, pp.103111, 2005-03

被引用文献数

38 40

---

We have investigated direct micromachining of quartz glass, using pulsed laser plasma soft x-rays (LPSXs) having a potential capability of nanomachining because the diffraction limit is ~10 nm. The LPSX's were generated by irradiation of a Ta target with 532 nm laser light from a conventional Q switched Nd:YAG laser at 700 mJ/pulse. In order to achieve a sufficient power density of LPSX's beyond the ablation threshold, we developed an ellipsoidal mirror to obtain efficient focusing of LPSXs at around 10 nm. It was found that quartz glass plates are smoothly ablated at 45 nm/shot using the focused and pulsed LPSX's.

著者

Hushur Anwar Shigematsu Hirotake Akishige Yukikuni Kojima Seiji

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.86, no.11, pp.112903, 2005-03

被引用文献数

28 25

---

Ferroelectric single crystals of BaTi2O5 have been studied in detail by Raman and high-resolution micro-Brillouin scattering with a focus on the central component of the relaxation mode over a wide temperature range (20–600 °C). A relaxation mode has been clearly observed in these single crystals. The temperature dependences of the relaxation time and integrated intensity of the relaxation mode are well reproduced by the extended semiclassical tunneling model. The ferroelectric phase transition shows, at least near the vicinity of Tc, an order-disorder nature. Our results indicate that the spontaneous polarization mainly resulted from the dynamic disorder of the Ti ions in the octahedra along the polar b axis of BaTi2O5.

著者

Shabbir Ghulam Ko Jae-Hyeon Kojima Seiji

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.86, no.1, pp.012908, 2004-12

被引用文献数

11 10

---

High-resolution Brillouin scattering experiments have been performed to investigate the low temperature "aging" effect in lanthanum lead zirconate titanate (PLZT) relaxor ferroelectric ceramics. From the temperature dependence of the frequency shift of longitudinal acoustic mode, an acoustic anomaly was observed at T0~46 K in these ceramics with clear "aging" effect below T0. The results have been discussed in the light of stepwise freezing of the related degrees of freedom causing transition from proper to improper dipole glassy states at T0.

著者

Yoshikawa M. Yasuhara R. Morimoto M. Shima Y. Kohagura J. Sakamoto M. Nakashima Y. Imai T. Yamada I. Kawahata K. Funaba H. Minami T.

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.83, no.10, pp.10E333, 2012-10

被引用文献数

17 6

---

In the GAMMA 10 tandem mirror, the typical electron density is comparable to that of the peripheral plasma of torus-type fusion devices. Therefore, an effective method to increase Thomson scattering (TS) signals is required in order to improve signal quality. In GAMMA 10, the yttrium-aluminum-garnet (YAG)-TS system comprises a laser, incident optics, light collection optics, signal detection electronics, and a data recording system. We have been developing a multi-pass TS method for a polarization-based system based on the GAMMA 10 YAG TS. To evaluate the effectiveness of the polarization-based configuration, the multi-pass system was installed in the GAMMA 10 YAG-TS system, which is capable of double-pass scattering. We carried out a Rayleigh scattering experiment and applied this double-pass scattering system to the GAMMA 10 plasma. The integrated scattering signal was made about twice as large by the double-pass system.

著者

Suzuki Kazuya Z. Yanagihara Hideto Niizeki Tomohiko Kojio Ken Kita Eiji

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.101, no.22, pp.222401, 2012-11

被引用文献数

5 4

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Magnetic and magnetotransport properties of pyromellitic dianhydride-4,4′-oxydianiline polyimide-Co granular thin films prepared by vapor deposition polymerization are investigated. The prepared sample is composed of Co particles with diameters of 2–3 nm homogeneously dispersed in a denatured polyimide matrix. The temperature dependence of the resistivity closely follows the T−1/2 law, suggesting that the dominant conduction mechanism is tunneling between metallic granules embedded in the insulating polyimide matrix. The magnetoresistances at 300 and 90 K are 2.6% and 3.0%, respectively. The results indicate that polyimide is a promising material for organic spintronics.

著者

Hojo H. Mase A.

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.77, no.10, pp.10F329, 2006-10

被引用文献数

1 1

---

A new method for determining the electron density of a thin plasma by means of Fabry-Pérot interferometry is proposed. The interferometer consists of two plasma layers and dielectric material surrounded by two plasma layers. The transmittance of electromagnetic waves across the interferometer is calculated, and Fabry-Pérot resonances are demonstrated. It is shown that the electron density can be determined from the measurement of the Fabry-Pérot resonance frequencies. This method can also be applied to the measurement of conduction electron density in semiconductor films.

著者

Handa Shinya Domalain Thierry Kose Katsumi

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.78, no.8, pp.084705, 2007-08

被引用文献数

16 14

---

An MRI pulse programmer has been developed using a single-chip microcontroller (ADμC7026). The microcontroller includes all the components required for the MRI pulse programmer: a 32-bit RISC CPU core, 62 Kbytes of flash memory, 8 Kbytes of SRAM, two 32-bit timers, four 12-bit DA converters, and 40 bits of general purpose I/O. An evaluation board for the microcontroller was connected to a host PC, an MRI transceiver, and a gradient driver using interface circuitry. Target (embedded) and host PC programs were developed to enable MRI pulse sequence generation by the microcontroller. The pulse programmer achieved a (nominal) time resolution of approximately 100 ns and a minimum time delay between successive events of approximately 9 μs. Imaging experiments using the pulse programmer demonstrated the effectiveness of our approach.

著者

Seki Yusuke Kandori Akihiko Kumagai Yukio Ohnuma Mitsuru Ishiyama Akihiko Ishii Tetsuko Nakamura Yoshiyuki Horigome Hitoshi Chiba Toshio

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.79, no.3, pp.036106, 2008-03

被引用文献数

11 14

---

We developed a fetal magnetocardiography (fMCG) system that uses a pair of two-dimensional gradiometers to achieve high signal-to-noise ratio. The gradiometer, which is based on a low-Tc superconducting quantum interference device, detects the gradient of a magnetic field in two orthogonal directions. Gradiometer position is easy to adjust by operating the gantry to drive the cryostat in both the swinging and axial directions. As a result, a fMCG waveform for 25 weeks' gestation was measured under an unshielded environment in real time. Moreover, the P and T waves for 25 and 34 weeks' gestation, respectively, were obtained by averaging. These results indicate that this two-dimensional gradiometer is one of the most promising techniques for measuring fetal heart rate and diagnosing fetal arrhythmia.

著者

Handa Shinya Haishi Tomoyuki Kose Katsumi

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.79, no.11, pp.113706, 2008-11

被引用文献数

10 6

---

A local radio frequency (rf) shielding consisting of a Cu plate and an LC balun circuit has been developed for a compact magnetic resonance imaging (MRI) system with a 0.3 T permanent magnet. Performance of the local rf shielding was evaluated using an artificial external noise source irradiating a human subject whose hand was inserted into the rf coil of the MRI system. Power spectra of the rf signal detected through the rf coil demonstrated that the local rf shield achieved 30.1 dB external noise suppression. With the local rf shielding, a MRI of the subject's hand was performed using a three-dimensional gradient-echo sequence. Anatomical structures of the subject's hand were clearly visualized. It was concluded that the local rf shielding could be used for the compact MRI system instead of a rf shielded room.

著者

Kimura Takeshi Geya Yuto Terada Yasuhiko Kose Katsumi Haishi Tomoyuki Gemma Hiroshi Sekozawa Yoshihiko

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.82, no.5, pp.053704, 2011-05

被引用文献数

46 12

---

By combining a 0.3 T permanent magnet with flexible rotation and translation mechanism, a probe with a local electromagnetic shielding, several electrical units, a mobile lift, and an electric wagon, a mobile magnetic resonance imaging (MRI) system was developed for outdoor tree measurements. 2D cross-sectional images of normal and diseased branches of a pear tree were acquired for measurements of T1, T2, proton density, and apparent diffusion constant (ADC). The ADC map clearly differentiated diseased from normal branches. A whole-day measurement of the ADC map demonstrated that microscopic water flow in the normal branch changed proportionally with solar radiation. Therefore, we have concluded that our mobile MRI system is a powerful tool for studies of plants in outdoor environments.

著者

Sakakibara Jun Kita Junichiro Osato Naoyuki

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.83, no.3, pp.036103, 2012-03

被引用文献数

15

---

We developed a video recording system with the capability of tracking moving objects and used it to track the flight of an insect. The system consists of two galvano mirrors, which redirect the light coming from the object in two orthogonal directions toward a high-speed camera to capture the image. An additional high-speed camera, which views the same object through a beam splitter placed between one of the galvano mirrors and the observation camera, detects the position of the object. The mirror angle is controlled to maintain the position of the object at the center of the view, allowing the object to be tracked. In order to validate this system, images of a live fly in flight were recorded along a flight path that was much longer than the field of view of the stationary camera. A high-resolution video image of a rapidly moving live fly was successfully captured.

著者

Makino Kotaro Tominaga Junji Kolobov Alexander V. Fons Paul Hase Muneaki

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.101, no.23, pp.232101, 2012-12

被引用文献数

15

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We report the optical perturbation of atomic arrangement in the layered in GeTe/Sb2Te3 phase change memory material. To observe the structural change, the coherent A1 mode of GeTe4 local structure was investigated at various polarization angles of femtosecond pump pulses with the fluence at ≤ 78 μJ/cm2. p-polarization found to be more effective in inducing the A1 frequency shift that can be either reversible or irreversible depending on the pump fluence. The predominant origin of this shift is attributed to rearrangement of Ge atoms driven by anisotropic dissociation of the Ge-Te bonds along the [111] axis after the p-polarized pulse irradiation.