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-Al
O
(0001)Entani, Shiro*; Honda, Mitsunori; Naramoto, Hiroshi*; Li, S.*; Sakai, Seiji*
Surface Science, 704, p.121749_1 - 121749_6, 2021/02
Times Cited Count：2 Percentile：32.21(Chemistry, Physical)Graphene is expected to be one of the most promising materials for nanoelectronics and spintronics. In most graphene-based devices, the graphene channel is placed on insulating substrates. Therefore, the study of inter-facial interactions between graphene and the insulator surface is of critical importance. In this study, the vertical arrangement of graphene which is transferred on -AlO(0001) has been studied by normal incidence X-ray standing wave (NIXSW) technique. The analysis of the NIXSW profile reveals that the graphene layer is located at 3.57 (
) above the -AlO(0001) surface, which is larger than the interlayer distance of graphite at 3.356 (). Micro- Raman spectroscopy shows that the transferred graphene has a limited spatial distribution of hole concentration. The present study shows that transferred graphene on the sapphire substrate followed by vacuum-annealing has an atomically flat surface free from residual contaminations such as organic compounds and there occurs the hole-doping in graphene.
Entani, Shiro*; Honda, Mitsunori; Shimoyama, Iwao; Li, S.*; Naramoto, Hiroshi*; Yaita, Tsuyoshi; Sakai, Seiji*
Japanese Journal of Applied Physics, 57(4S), p.04FP04_1 - 04FP04_4, 2018/04
Times Cited Count：3 Percentile：17.87(Physics, Applied)Fukaya, Yuki; Entani, Shiro; Sakai, Seiji; Mochizuki, Izumi*; Wada, Ken*; Hyodo, Toshio*; Shamoto, Shinichi
Carbon, 103, p.1 - 4, 2016/07
Times Cited Count：19 Percentile：58.51(Chemistry, Physical)no abstracts in English
Haku, Satoshi*; Tashiro, Takaharu*; Nakayama, Hiroyasu*; Ieda, Junichi; Entani, Shiro; Sakai, Seiji; Ando, Kazuya*
Applied Physics Express, 8(7), p.073009_1 - 073009_3, 2015/07
Times Cited Count：4 Percentile：15.06(Physics, Applied)We found that the spin pumping in a Ni
Fe
/Pt bilayer is strongly suppressed by inserting single-layer graphene (SLG) at the interface. The spin pumping in the NiFe/Pt bilayer enhances the magnetization damping of the ferromagnetic layer, which is quantified from microwave frequency dependence of ferromagnetic resonance linewidth. We show that the enhancement of the magnetization damping due to the spin pumping disappears in a NiFe/SLG/Pt trilayer. This result indicates that the spin pumping is blocked by the atomic monolayer, demonstrating the crucial role of the interfacial short-range spin-exchange coupling in the spin pumping in metallic systems.
Entani, Shiro; Naramoto, Hiroshi*; Sakai, Seiji
Journal of Applied Physics, 117(17), p.17A334_1 - 17A334_4, 2015/05
Times Cited Count：19 Percentile：65.08(Physics, Applied)Entani, Shiro; Antipina, L. Y.*; Avramov, P.*; Otomo, Manabu*; Matsumoto, Yoshihiro*; Hirao, Norie; Shimoyama, Iwao; Naramoto, Hiroshi*; Baba, Yuji; Sorokin, P. B.*; et al.
Nano Research, 8(5), p.1535 - 1545, 2015/05
Times Cited Count：22 Percentile：69.66(Chemistry, Physical)Kuzubov, A. A.*; Kovaleva, E. A.*; Avramov, P. V.*; Kuklin, A. V.*; Mikhaleva, N. S.*; Tomilin, F. N.*; Sakai, Seiji; Entani, Shiro; Matsumoto, Yoshihiro*; Naramoto, Hiroshi*
Journal of Applied Physics, 116(8), p.084309_1 - 084309_4, 2014/08
Times Cited Count：9 Percentile：40.37(Physics, Applied)Avramov, P. V.*; Kuzubov, A. A.*; Sakai, Seiji; Otomo, Manabu*; Entani, Shiro; Matsumoto, Yoshihiro*; Eleseeva, N. S.*; Pomogaev, V. A.*; Naramoto, Hiroshi*
Journal of Porphyrins and Phthalocyanines, 18(7), p.552 - 568, 2014/07
Times Cited Count：1 Percentile：4.91(Chemistry, Multidisciplinary)Otomo, Manabu; Yamauchi, Yasushi*; Kuzubov, A. A.*; Eliseeva, N. S.*; Avramov, P.*; Entani, Shiro; Matsumoto, Yoshihiro; Naramoto, Hiroshi*; Sakai, Seiji
Applied Physics Letters, 104(5), p.051604_1 - 051604_4, 2014/02
Times Cited Count：12 Percentile：49.61(Physics, Applied)Hexagonal boron nitride (h-BN) is a promising barrier material for graphene spintronics. In this study, spin-polarized metastable de-excitation spectroscopy (SPMDS) is employed to study the spin-dependent electronic structure of monolayer h-BN on Ni(111). The extreme surface sensitivity of SPMDS enables us to elucidate a partial filling of the in-gap states of h-BN without any superposition of Ni 3
signals. The in-gap states are shown to have a considerable spin polarization parallel to the majority spin of Ni. The positive spin polarization is attributed to the 
- hybridization and the effective spin transfer to the nitrogen atoms at the h-BN/Ni(111) interface.
Entani, Shiro; Kurahashi, Mitsunori*; Sun, X.*; Yamauchi, Yasushi*
Carbon, 61, p.134 - 139, 2013/09
Times Cited Count：17 Percentile：51.42(Chemistry, Physical)Matsumoto, Yoshihiro; Entani, Shiro; Koide, Akihiro*; Otomo, Manabu; Avramov, P.; Naramoto, Hiroshi*; Amemiya, Kenta*; Fujikawa, Takashi*; Sakai, Seiji
Journal of Materials Chemistry C, 1(35), p.5533 - 5537, 2013/09
Times Cited Count：28 Percentile：75.33(Materials Science, Multidisciplinary)
interface in the Fe-doped C filmSakai, Seiji; Matsumoto, Yoshihiro; Otomo, Manabu; Entani, Shiro; Avramov, P.; Sorokin, P. B.*; Naramoto, Hiroshi*
Synthetic Metals, 173, p.22 - 25, 2013/06
Times Cited Count：2 Percentile：10.96(Materials Science, Multidisciplinary)
-BN/Ni nanocompositesAvramov, P.; Kuzubov, A. A.*; Sakai, Seiji; Otomo, Manabu; Entani, Shiro; Matsumoto, Yoshihiro; Naramoto, Hiroshi*; Eliseeva, N. S.*
Journal of Applied Physics, 112(11), p.114303_1 - 114303_10, 2012/12
Times Cited Count：16 Percentile：57.37(Physics, Applied)Avramov, P.; Fedorov, D. G.*; Sorokin, P. B.*; Sakai, Seiji; Entani, Shiro; Otomo, Manabu; Matsumoto, Yoshihiro; Naramoto, Hiroshi*
Journal of Physical Chemistry Letters (Internet), 3(15), p.2003 - 2008, 2012/08
Times Cited Count：32 Percentile：77.81(Chemistry, Physical)Antipina, L. Y.*; Avramov, P.; Sakai, Seiji; Naramoto, Hiroshi*; Otomo, Manabu; Entani, Shiro; Matsumoto, Yoshihiro; Sorokin, P. B.*
Physical Review B, 86(8), p.085435_1 - 085435_7, 2012/08
Times Cited Count：48 Percentile：86.62(Materials Science, Multidisciplinary)-Co films with current-perpendicular-to-plane geometrySakai, Seiji; Mitani, Seiji*; Matsumoto, Yoshihiro; Entani, Shiro; Avramov, P.; Otomo, Manabu; Naramoto, Hiroshi*; Takanashi, Koki
Journal of Magnetism and Magnetic Materials, 324(12), p.1970 - 1974, 2012/06
Times Cited Count：3 Percentile：15.52(Materials Science, Multidisciplinary)Baba, Yuji; Narita, Ayumi; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Hirao, Norie; Entani, Shiro; Sakai, Seiji
e-Journal of Surface Science and Nanotechnology (Internet), 10, p.69 - 73, 2012/04
We report on the first results for the geometrical determination of adsorbed atoms on an oxide by a soft-X-ray sanding wave method. The samples investigated were alkyl phosphonic acid (C10) adsorbed on a sapphire surface, which is one of the candidate systems for organic self-assembled monolayer (SAM) on oxides. The surface was irradiated by synchrotron soft X-rays from the surface normal. The intensity of photoelectrons was plotted as a function of the photon energy. We observed clear profiles of the photoelectron intensity due to the standing wave from the substrate. Compared with the simulation using the crystal parameters, it was found that the phosphorus atoms are located at 0.11 nm from the surface, while the constant height was not observed for carbon atoms. The results are in consistent with the results by XPS and NEXAFS; the molecules form SAM on the sapphire surface with phosphonic acids and alkyl chains are located at the upper side.
Entani, Shiro; Matsumoto, Yoshihiro; Otomo, Manabu; Avramov, P.; Naramoto, Hiroshi*; Sakai, Seiji
Journal of Applied Physics, 111(6), p.064324_1 - 064324_6, 2012/03
Times Cited Count：18 Percentile：61.23(Physics, Applied)
analysis was performed on the graphene growth in ultrahigh vacuum chemical vapor deposition by exposing the epitaxial Ni(111) thin film to benzene vapor at 873 K. It is shown that the highly uniform single- and bi-layer graphenes can be synthesized by the control of benzene exposure in the range of 10-10
langmuirs, reflecting a change in the graphene growth-rate by three orders of magnitude in between the first and second layer. Electron energy loss spectroscopy measurements of single- and bi-layer graphenes indicates that the interface interaction between bi-layer graphene and Ni(111) is weakened in comparison with that between single-layer graphene and Ni(111). It is also clarified from the micro-Raman analysis that the structural and electrical uniformities of the graphene film transformed on a SiO substrate are improved remarkably under the specific exposure conditions at which the growths of single- and bi-layer graphenes are completed.
Hojo, Ikuko*; Koide, Akihiro*; Matsumoto, Yoshihiro; Maruyama, Takashi*; Nagamatsu, Shinichi*; Entani, Shiro; Sakai, Seiji; Fujikawa, Takashi*
Journal of Electron Spectroscopy and Related Phenomena, 185(1-2), p.32 - 38, 2012/03
Times Cited Count：1 Percentile：7.71(Spectroscopy)Nishiuchi, Mamiko; Pirozhkov, A. S.; Sakaki, Hironao; Ogura, Koichi; Esirkepov, T. Z.; Tanimoto, Tsuyoshi; Kanasaki, Masato; Yogo, Akifumi; Hori, Toshihiko; Sagisaka, Akito; et al.
Physics of Plasmas, 19(3), p.030706_1 - 030706_4, 2012/03
Times Cited Count：6 Percentile：27.32(Physics, Fluids & Plasmas)A 7 MeV proton beam collimated to 16 mrad containing more than 
particles is experimentally demonstrated by focusing a 2J, 60 fs pulse of a Ti:sapphire laser onto targets of different materials and thicknesses placed in a millimeter scale conical holder. The electric potential induced on the target holder by laser-driven electrons accelerates and dynamically controls a portion of a divergent quasi-thermal proton beam originated from the target, producing a quasi-monoenergetic "pencil" beam.
