Tomohiro Kobayashi
Aoyama Gakuin University
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Publication
Featured researches published by Tomohiro Kobayashi.
Japanese Journal of Applied Physics | 2010
Takeshi Yajima; Kohei Fujiwara; Aiko Nakao; Tomohiro Kobayashi; Toshiyuki Tanaka; Kei Sunouchi; Yoshiaki Suzuki; Mai Takeda; K. Kojima; Yoshinobu Nakamura; Kouji Taniguchi; Hidenori Takagi
The change in the spatial distribution of oxygen ions after an initial voltage application called the forming process was investigated for oxide resistance switching devices by secondary ion mass spectrometry mapping. To track the motion of oxygen ions, tracer 18O ions were implanted in a planar Pt/CuO/Pt device. We found clear evidence for the oxygen reduction in the conductive bridge structure formed between two electrodes. In addition, the oxygen ions in the bridge structure drift to the anode, implying the oxygen diffusion (migration) induced by high electric field and/or current density. We discuss those results in terms of a filament model.
Japanese Journal of Applied Physics | 2006
Mina Ryo; Yusuke Sakurai; Tomohiro Kobayashi; Hajime Shirai
The rapid recrystallization of amorphous silicon (a-Si) utilizing a very-high-frequency (VHF) plasma jet of argon (Ar) at atmospheric pressure is investigated. A highly crystallized polycrystalline Si film is synthesized by optimizing the translating velocity of the substrate stage and the flow rate of argon. The temperature of the plasma exposure area reaches 1350±300 °C and the recrystallization of a-Si proceeded with time constants of 30–50 ms. The effects of the translating velocity of the substrate stage and the flow rate of argon on the rapid recrystallization of a-Si are demonstrated along with its mechanism.
Japanese Journal of Applied Physics | 2005
Hajime Shirai; Tomoyuki Kikuchi; Tomohiro Kobayashi
Growth of vertically well-aligned carbon nanotubes was demonstrated utilizing high-density rf inductive coupling plasma-enhanced chemical vapor deposition of methane. A sufficient supply of CH4-related precursors as well as a rapid large number of dangling bonds at the top surface due to a negative substrate dc bias are essential for promoting the deposition rate of vertically well-aligned carbon nanotubes. Rapid deposition at 60 A/s of vertically well-aligned multi-walled carbon nanotubes was achieved using pure methane (50 sccm) by adjusting the plasma conditions.
Physica B-condensed Matter | 1990
Shunji Sugai; Masatoshi Sato; Takashi Ito; T. Ido; Hidenori Takagi; Shin-ichi Uchida; Tomohiro Kobayashi; Jun Akimitsu; Y. Hidaka; T. Murakami; S. Hosoya; Tsuyoshi Kajitani; T. Fukuda
The spin and doped charge states in copper oxide superconductors were investigated by Raman spectroscopy. The anomalous magnon scattering in the antiferromagnetic insulator phases, such as the second peaks near 4J (J is the two-spin superexchange energy) in the B1g spectra and the large scattering intensities in the A1g spectra, suggests the existence of four-spin cyclic exchange interactions. When carriers are doped, the A1g spectra show non-“normal Fermi liquid” behavior. The imaginary part of the experimentally obtained susceptibility have ω-proportional part from ω~0. The gradient increases, on cooling, as in the case of the marginal Fermi liquid.
Journal of Magnetism and Magnetic Materials | 1990
Shunji Sugai; Masatoshi Sato; T. Itoc; T. Ido; H. Takagi; S. Uchida; Tomohiro Kobayashi; Jun Akimitsu; Y. Hidaka; T. Murakami; S. Hosoya; Tsuyoshi Kajitani; T. Fukuda
Raman spectra in the antiferromagnetic insulator phases of s = 1/2 high T c superconducting cuprates were compared with s = 1 La 2 NiO 4 . The anomalous magnon spectra in cuprates suggest that the four-spin cyclic exchange interactions are very large. The doped carriers in cuprates show non-Fermi liquid behavior.
Physica Status Solidi (a) | 2010
Naoki Ohta; Takashi Imamura; Hirokazu Shimizu; Tomohiro Kobayashi; Hajime Shirai
Meeting Abstracts | 2009
Yi Ding; Hajime Shirai; Fangli Yuan; Tomohiro Kobayashi
Meeting Abstracts | 2009
Naoki Ota; Takashi Imamura; Hirokazu Shimizu; Tomohiro Kobayashi; Hajime Shirai
216th ECS Meeting | 2009
Naoki Ota; Koji Haruta; Hirokazu Shimizu; Tomohiro Kobayashi; Hajime Shirai
216th ECS Meeting | 2009
Yi Ding; Tomohiro Kobayashi; Haijun Jia; Hajime Shirai