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19 results on '"Goto, Arihiro"'

1. Complex structural dynamics of bismuth under laser-driven compression

Author

Hu, Jianbo, Ichiyanagi, Kouhei, Doki, Tomoaki, Goto, Arihiro, Eda, Takayuki, Norimatsu, Katsura, Harada, Shinichi, Horiuchi, Dai, Kabasawa, Yuki, Hayashi, Shingo, Uozumi, Shin-ichi, Kawai, Nobuaki, Nozawa, Shunsuke, Sato, Tokushi, Adachi, Shin-ichi, and Nakamura, Kazutaka G.

Subjects
Condensed Matter - Materials Science
Abstract

With the aid of nanosecond time-resolved X-ray diffraction techniques, we have explored the complex structural dynamics of bismuth under laser-driven compression. The results demonstrate that shocked bismuth undergoes a series of structural transformations involving four solid structures: the Bi-I, Bi-II, Bi-III and Bi-V phases. The transformation from the Bi-I phase to the Bi-V phase occurs within 4 ns under shock compression at ~11 GPa, showing no transient phases with the available experimental conditions. Successive phase transitions (Bi-V->Bi-III->Bi-II->Bi-I) during the shock release within 30 ns have also been resolved, which were inaccessible using other dynamic techniques., Comment: 17 pages, 4 figures, Appl. Phys. Lett. accepted

Published
2013
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2. Delayed formation of coherent LO phonon-plasmon coupled modes in n-type and p-type GaAs measured using a femtosecond coherent control technique

Author

Hu, Jianbo, Misochko, Oleg V., Goto, Arihiro, and Nakamura, Kazutaka G.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Strongly Correlated Electrons
Abstract

Coherent control experiments using a pair of collinear femtosecond laser pulses have been carried out to manipulate longitudinal optical (LO) phonon-plasmon coupled (LOPC) modes in both p- and n-type GaAs. By tuning the interpulse separation, remarkably distinct responses have been observed in the two samples. To understand the results obtained a phenomenological model taking the delayed formation of coherent LOPC modes into account is proposed. The model suggests that the lifetime of coherent LOPC modes plays a key role and the interference of the coherent LO phonons excited successively by two pump pulses strongly affects the manipulation of coherent LOPC modes., Comment: 19 pages, 6 figures, accepted for publication in Phys. Rev. B

Published
2011
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3. Dynamics of optical phonons in Bi2Se3 crystal studied using femtosecond time-resolved reflection measurement

Author

Sasagawa Takao, Igarashi Kyushiro, Hu Jianbo, Goto Arihiro, Norimatsu Katsura, and Nakamura Kazutaka G.

Subjects
Physics, QC1-999
Abstract

The dynamics of coherent optical phonons (A1g1, A1g2 and Eg2) in Bi2Se3 single crystal have been observed by using femtosecond time-resolved reflection measurement. The phonons with the higher frequency have the faster damping rate (decay faster). The A1g2 phonons show cosine-like oscillation, while the A1g1 and Eg2 phonons show cosine-like oscillation. The difference in the initial phase suggests that the potential energy surface may shift significantly along the A1g2 eigenvector and little along the A1g1 and Eg2 eigenvectors in the excited state.

Published
2013
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6. Complex structural dynamics of bismuth under laser-driven compression

Author

Hu, Jianbo, primary, Ichiyanagi, Kouhei, additional, Doki, Tomoaki, additional, Goto, Arihiro, additional, Eda, Takayuki, additional, Norimatsu, Katsura, additional, Harada, Shinichi, additional, Horiuchi, Dai, additional, Kabasawa, Yuki, additional, Hayashi, Shingo, additional, Uozumi, Shin-ichi, additional, Kawai, Nobuaki, additional, Nozawa, Shunsuke, additional, Sato, Tokushi, additional, Adachi, Shin-ichi, additional, and Nakamura, Kazutaka G., additional

Published
2013
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14. Dynamics of optical phonons in Bi2Se3 crystal studied using femtosecond time-resolved reflection measurement.

Author

Norimatsu, Katsura, Hu, Jianbo, Goto, Arihiro, Igarashi, Kyushiro, Sasagawa, Takao, and Nakamura, Kazutaka G.

Subjects
DYNAMICS, PHONONS, FEMTOSECOND pulses, TIME-resolved measurements, FREQUENCIES of oscillating systems, OSCILLATIONS, POTENTIAL energy surfaces, EIGENVECTORS
Abstract

The dynamics of coherent optical phonons (A1g1, A1g2 and Eg2) in Bi2Se3 single crystal have been observed by using femtosecond time-resolved reflection measurement. The phonons with the higher frequency have the faster damping rate (decay faster). The A1g2 phonons show cosine-like oscillation, while the A1g1 and Eg2 phonons show cosine-like oscillation. The difference in the initial phase suggests that the potential energy surface may shift significantly along the A1g2 eigenvector and little along the A1g1 and Eg2 eigenvectors in the excited state. [ABSTRACT FROM AUTHOR]

Published
2013
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15. Manipulating coherent LO phonons and phonon-plasmon coupling in highly doped p-GaAs.

Author

Hu, Jianbo, Misochko, Oleg V., Goto, Arihiro, and Nakamura, Kazutaka G.

Abstract

Femtosecond laser pulses are employed to coherently control the LO phonon strength and lifetime of LO phonon-plasmon coupled modes in a highly doped p-GaAs. The change in lifetime might be due to Landau damping. [ABSTRACT FROM PUBLISHER]

Published
2012

16. Dynamics of coherent optical phonons in a Bi2Se3 crystal.

Author

Norimatsu, Katsura, Hu, Jianbo, Goto, Arihiro, Igarashi, Kyushiro, Sasagawa, Takao, and Nakamura, Kazutaka G.

Abstract

Coherent A1g1, A1g2, and Eg2 phonons in Bi2Se3 are observed using ultrafast spectroscopy. Their initial phases suggest different coupling strengths with photo-excited electrons. Their decay rates per oscillations are almost the same. [ABSTRACT FROM PUBLISHER]

Published
2012

17. Coherent optical phonons in a Bi2Se3 single crystal measured via transient anisotropic reflectivity

Author

Norimatsu, Katsura, Hu, Jianbo, Goto, Arihiro, Igarashi, Kyushiro, Sasagawa, Takao, and Nakamura, Kazutaka G.

Subjects
*PHONONS, *COHERENCE (Optics), *BISMUTH selenide, *SINGLE crystals, *ANISOTROPY, *REFLECTANCE, *TRANSIENTS (Dynamics), *MEASUREMENT
Abstract

Abstract: Coherent optical Eg phonons in a Bi2Se3 single crystal have been observed by using femtosecond transient anisotropic reflection measurements in addition to A1g 1 and A1g 2 phonons. Frequency, damping rate, and initial phase of coherent oscillations of phonons are obtained. The phonons with the higher frequency have the faster damping rate. The A1g 2 phonons show cosine-like oscillation, while the A1g 1 and Eg 2 phonons show sine-like oscillation. These differences in the initial phase suggest that the nonequilibrium carrier distribution may shift the potential energy surface significantly along the A1g 2 eigenvector and little along the A1g 1 and Eg 2 eigenvectors in the excited state. [Copyright &y& Elsevier]

Published
2013
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18. Delayed formation of coherent LO phonon-plasmon coupled modes in n- and p-type GaAs measured using a femtosecond coherent control technique.

Author

Jianbo Hu, Misochko, Oleg V., Goto, Arihiro, and Nakamura, Kazutaka G.

Subjects
*GALLIUM arsenide, *PHONONS, *PLASMONS (Physics), *FEMTOSECOND pulses, *SOLID state physics
Abstract

Coherent control experiments using a pair of collinear femtosecond laser pulses have been carried out to manipulate longitudinal optical (LO) phonon-plasmon coupled (LOPC) modes in both p- and n-type GaAs. By tuning the interpulse separation, remarkably distinct responses have been observed in the two samples. To understand the results obtained a phenomenological model taking the delayed formation of coherent LOPC modes into account is proposed. The model suggests that the lifetime of coherent LOPC modes plays a key role and the interference of the coherent LO phonons excited successively by two pump pulses strongly affects the manipulation of coherent LOPC modes. [ABSTRACT FROM AUTHOR]

Published
2012
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19. Observation of coherent higher frequency phonons in Bi2Se3 using femtosecond time-resolved reflection measurement

Author

Nakamura, Kazutaka G., Hu, Jianbo, Norimatsu, Katsura, Goto, Arihiro, Igarashi, Kyushiro, and Sasagawa, Takao

Subjects
*SELENIDES, *BISMUTH compounds, *SCIENTIFIC observation, *PHONONS, *TIME-resolved measurements, *OPTICAL reflection, *TEMPERATURE effect
Abstract

Abstract: The dynamics of phonons in a Bi2Se3 crystal has been studied by using femtosecond time-resolved reflection measurements. Two coherent optical phonons with and modes are observed at 2.14 and 5.09 THz at room temperature, respectively. The initial amplitude of the generated coherent phonons is higher than that of the phonons, but those are quickly damped with a rate of 1.28 THz. [Copyright &y& Elsevier]

Published
2012
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