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Journal Articles

Total-reflection high-energy positron diffraction (TRHEPD) for structure determination of the topmost and immediate sub-surface atomic layers

Fukaya, Yuki; Kawasuso, Atsuo*; Ichimiya, Ayahiko*; Hyodo, Toshio*

Journal of Physics D; Applied Physics, 52(1), p.013002_1 - 013002_19, 2019/01

 Times Cited Count:2 Percentile:82.23(Physics, Applied)

no abstracts in English

Journal Articles

Research progress at the Slow Positron Facility in the Institute of Materials Structure Science, KEK

Hyodo, Toshio*; Wada, Ken*; Mochizuki, Izumi*; Kimura, Masao*; Toge, Nobukazu*; Shidara, Tetsuo*; Fukaya, Yuki; Maekawa, Masaki*; Kawasuso, Atsuo*; Iida, Shimpei*; et al.

Journal of Physics; Conference Series, 791(1), p.012003_1 - 012003_8, 2017/02

 Times Cited Count:2 Percentile:21.93

no abstracts in English

Journal Articles

Structure determination of the rutile-TiO$$_{2}$$(110)(1$$times$$2) surface using total-reflection high-energy positron diffraction (TRHEPD)

Mochizuki, Izumi*; Ariga, Hiroko*; Fukaya, Yuki; Wada, Ken*; Maekawa, Masaki*; Kawasuso, Atsuo*; Shidara, Tetsuo*; Asakura, Kiyotaka*; Hyodo, Toshio*

Hyomen Kagaku, 37(9), p.451 - 456, 2016/09

no abstracts in English

Journal Articles

Structure determination of the rutile-TiO$$_{2}$$(110)-(1$$times$$2) surface using total-reflection high-energy positron diffraction (TRHEPD)

Mochizuki, Izumi*; Ariga, Hiroko*; Fukaya, Yuki; Wada, Ken*; Maekawa, Masaki; Kawasuso, Atsuo; Shidara, Tetsuo*; Asakura, Kiyotaka*; Hyodo, Toshio*

Physical Chemistry Chemical Physics, 18(10), p.7085 - 7092, 2016/03

 Times Cited Count:12 Percentile:33.39(Chemistry, Physical)

no abstracts in English

Journal Articles

Applications of spin-polarized positron beam

Kawasuso, Atsuo

Hoshasen To Sangyo, (139), p.18 - 22, 2015/12

no abstracts in English

Journal Articles

Effect of magnetic field on positron lifetimes of Fe, Co and Ni

Li, H.; Maekawa, Masaki; Kawasuso, Atsuo; Tanimura, Naoki*

Journal of Physics; Condensed Matter, 27(24), p.246001_1 - 246001_5, 2015/06

 Times Cited Count:6 Percentile:67.64(Physics, Condensed Matter)

Journal Articles

Charge-to-spin conversion and spin diffusion in Bi/Ag bilayers observed by spin-polarized positron beam

Zhang, H. J.; Yamamoto, Shunya; Gu, B.; Li, H.; Maekawa, Masaki; Fukaya, Yuki; Kawasuso, Atsuo

Physical Review Letters, 114(16), p.166602_1 - 166602_5, 2015/04

 Times Cited Count:30 Percentile:12.31(Physics, Multidisciplinary)

Charge-to-spin conversion induced by the Rashba-Edelstein effect was directly observed for the first time in samples with no magnetic layer. A spin-polarized positron beam was used to probe the spin polarization of the outermost surface electrons of Bi/Ag/Al$$_2$$O$$_3$$ and Ag/Bi/Al$$_2$$O$$_3$$ when charge currents were only associated with the Ag layers. An opposite surface spin polarization was found between Bi/Ag/Al$$_2$$O$$_3$$ and Ag/Bi/Al$$_2$$O$$_3$$ samples with the application of a charge current in the same direction. The surface spin polarizations of both systems decreased exponentially with the outermost layer thickness, suggesting the occurrence of spin diffusion from the Bi/Ag interface to the outermost surfaces. This work provides a new technique to measure spin diffusion length.

Journal Articles

Enhanced damage buildup in C$$^{+}$$-implanted GaN film studied by a monoenergetic positron beam

Li, X. F.*; Chen, Z. Q.*; Liu, C.*; Zhang, H.; Kawasuso, Atsuo

Journal of Applied Physics, 117(8), p.085706_1 - 085706_6, 2015/02

 Times Cited Count:21 Percentile:21.69(Physics, Applied)

Vacancy-type defects in C$$^{+}$$-implanted GaN were probed using a slow positron beam. The increase of Doppler broadening S parameter indicates introduction of arge vacancy clusters. Post-implantation annealing at temperatures up to 800$$^{circ}$$C makes these vacancy clusters to agglomerate into microvoids. The vacancy clusters or microvoids show high thermal stability, and they are only partially removed after annealing up to 1000$$^{circ}$$C. Amorphous regions are observed by high resolution transmission electron microscopy measurement, which directly confirms that amorphization is induced by C$$^{+}$$-implantation. The disordered GaN lattice is possibly due to special feature of carbon impurities, which enhance the damage buildup during implantation.

Journal Articles

Radioisotope-based spin-polarized positron beam

Kawasuso, Atsuo

Yodenshi Kagaku, (4), p.9 - 22, 2015/02

In this article, I report, the spin polarization of positrons emitted from radioisotopes, the development of spin-polarized beams, the fundamental aspects of spin-polarized positron annihilation method, and, the investigation of current-induced spin polarization on metal surfaces through the spin-polarized positronium annihilation.

Journal Articles

Journal Articles

Total reflection high-energy positron diffraction; An Ideal diffraction technique for surface structure analysis

Fukaya, Yuki; Maekawa, Masaki; Kawasuso, Atsuo; Mochizuki, Izumi*; Wada, Ken*; Shidara, Tetsuo*; Ichimiya, Ayahiko*; Hyodo, Toshio*

Applied Physics Express, 7(5), p.056601_1 - 056601_4, 2014/05

 Times Cited Count:15 Percentile:35.07(Physics, Applied)

no abstracts in English

Journal Articles

Reflection high-energy positron diffraction study on the first surface layer

Fukaya, Yuki; Maekawa, Masaki; Mochizuki, Izumi*; Wada, Ken*; Hyodo, Toshio*; Kawasuso, Atsuo

Journal of Physics; Conference Series, 505, p.012005_1 - 012005_6, 2014/04

 Times Cited Count:1 Percentile:42.22

no abstracts in English

Journal Articles

Spin polarizations of positron beams generated using electrostatic and magnetic transportation systems with $$^{68}$$Ge and $$^{22}$$Na sources

Maekawa, Masaki; Fukaya, Yuki; Zhang, H.; Li, H.; Kawasuso, Atsuo

Journal of Physics; Conference Series, 505, p.012033_1 - 012033_4, 2014/04

 Times Cited Count:6 Percentile:6.69

Journal Articles

Total reflection high-energy positron diffraction (TRHEPD)

Hyodo, Toshio*; Fukaya, Yuki; Maekawa, Masaki; Mochizuki, Izumi*; Wada, Ken*; Shidara, Tetsuo*; Ichimiya, Ayahiko*; Kawasuso, Atsuo

Journal of Physics; Conference Series, 505(1), p.012001_1 - 012001_5, 2014/04

 Times Cited Count:5 Percentile:8.89

no abstracts in English

Journal Articles

Current-induced spin polarization on metal surfaces probed by spin-polarized positron beam

Zhang, H.; Yamamoto, Shunya; Fukaya, Yuki; Maekawa, Masaki; Li, H.; Kawasuso, Atsuo; Seki, Takeshi*; Saito, Eiji*; Takanashi, Koki*

Scientific Reports (Internet), 4, p.4844_1 - 4844_5, 2014/04

 Times Cited Count:30 Percentile:16.91(Multidisciplinary Sciences)

Journal Articles

Structure of silicene on a Ag(111) surface studied by reflection high-energy positron diffraction

Fukaya, Yuki; Mochizuki, Izumi*; Maekawa, Masaki; Wada, Ken*; Hyodo, Toshio*; Matsuda, Iwao*; Kawasuso, Atsuo

Physical Review B, 88(20), p.205413_1 - 205413_4, 2013/11

 Times Cited Count:54 Percentile:7.9(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Current-induced spin polarization on a Pt surface; A New approach using spin-polarized positron annihilation spectroscopy

Kawasuso, Atsuo; Fukaya, Yuki; Maekawa, Masaki; Zhang, H.; Seki, Takeshi*; Yoshino, Tatsuro*; Saito, Eiji*; Takanashi, Koki*

Journal of Magnetism and Magnetic Materials, 342, p.139 - 143, 2013/09

 Times Cited Count:18 Percentile:32.95(Materials Science, Multidisciplinary)

Transversely spin-polarized positrons were injected near Pt and Au surfaces under an applied electric current. The three-photon annihilation of spin-triplet positronium, which was emitted from the surfaces into vacuum, was observed. When the positron spin polarization was perpendicular to the current direction, the maximum asymmetry of the three-photon annihilation intensity was observed upon current reversal for the Pt surfaces, whereas it was significantly reduced for the Au surface. The experimental results suggest that electrons near the Pt surfaces were in-plane and transversely spin-polarized with respect to the direction of the electric current. The maximum electron spin polarization was estimated to be more than 0.01 (1%).

Journal Articles

Development of spin-polarized slow positron beam using a $$^{68}$$Ge-$$^{68}$$Ga positron source

Maekawa, Masaki; Fukaya, Yuki; Yabuuchi, Atsushi; Mochizuki, Izumi; Kawasuso, Atsuo

Nuclear Instruments and Methods in Physics Research B, 308, p.9 - 14, 2013/08

 Times Cited Count:12 Percentile:25.6(Instruments & Instrumentation)

Journal Articles

Spin-polarized positron annihilation spectroscopy for spintronics applications

Kawasuso, Atsuo; Fukaya, Yuki; Maekawa, Masaki; Mochizuki, Izumi; Zhang, H.

Journal of Physics; Conference Series, 443(1), p.012084_1 - 012084_4, 2013/06

 Times Cited Count:3 Percentile:26.54

Spin-polarized positrons are useful in studying spintronics materials. We are producing positron sources for highly polarized positrons and are developing polarized positron beams using those sources. We investigated some ferromagnets and found that their electron momentum distributions exhibit field-reversal asymmetry. We also found a strong current-induced spin accumulation on Pt surfaces.

Journal Articles

Reflection high-energy positron diffraction; The Past 15 years and the future

Fukaya, Yuki; Maekawa, Masaki; Mochizuki, Izumi; Wada, Ken*; Hyodo, Toshio*; Kawasuso, Atsuo

Journal of Physics; Conference Series, 443(1), p.012068_1 - 012068_6, 2013/06

 Times Cited Count:11 Percentile:2.85

no abstracts in English

480 (Records 1-20 displayed on this page)