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Sumida, Kazuki; Sakuraba, Yuya*; Kimura, Akio*
Kotai Butsuri, 58(3), p.117 - 137, 2023/03
no abstracts in English
MnGa thin films underneath a protection layerKono, Takashi*; Kakoki, Masaaki*; Yoshikawa, Tomoki*; Wang, X.*; Sumida, Kazuki; Muro, Takayuki*; Goto, Kazuki*; Sakuraba, Yuya*; Umetsu, Rie*; Kimura, Akio*
Physical Review B, 104(19), p.195112_1 - 195112_8, 2021/11
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)Angle-resolved photoelectron spectroscopy utilizing soft X-ray synchrotron radiation was applied to Heusler-type CoMnGa thin films that have a 1-nm Al capping layer. The bulk Fermi surfaces and band structures varied along the out-of-plane momentum, stemming from the three-dimensional crystal structure, in the absence of any in situ surface treatment. In addition, there were characteristic intersecting bands (Weyl cones), with crossing points near the Fermi level, which were consistent with computed results. The Weyl cones are of bulk origin and are responsible for the high anomalous Nernst and the anomalous Hall coefficients. A close comparison of the experimental band structures in CoMnGe and CoMnGa indicated that the rigid band picture is valid in both alloys and that fine carrier tuning is possible by replacing Ga with Ge to improve the anomalous conductivity.
Sumida, Kazuki; Sakuraba, Yuya*; Masuda, Keisuke*; Kono, Takashi*; Kakoki, Masaaki*; Goto, Kazuki*; Zhou, W.*; Miyamoto, Koji*; Miura, Yoshio*; Okuda, Taichi*; et al.
Communications Materials (Internet), 1, p.89_1 - 89_9, 2020/11
MnGe (Ga) film via Ge (Ga) 
absorption spectroscopyYoshikawa, Tomoki*; Antonov, V. N.*; Kono, Takashi*; Kakoki, Masaaki*; Sumida, Kazuki; Miyamoto, Koji*; Takeda, Yukiharu; Saito, Yuji; Goto, Kazuki*; Sakuraba, Yuya*; et al.
Physical Review B, 102(6), p.064428_1 - 064428_7, 2020/08
Times Cited Count：1 Percentile：7.06(Materials Science, Multidisciplinary)MnGe revealed by resonant photoelectron spectroscopyKono, Takashi*; Kakoki, Masaaki*; Yoshikawa, Tomoki*; Wang, X.*; Sumida, Kazuki*; Miyamoto, Koji*; Muro, Takayuki*; Takeda, Yukiharu; Saito, Yuji; Goto, Kazuki*; et al.
Physical Review B, 100(16), p.165120_1 - 165120_6, 2019/10
Times Cited Count：4 Percentile：24.12(Materials Science, Multidisciplinary)MnSiChudo, Hiroyuki; Ando, Kazuya*; Saito, Kesami*; Okayasu, Satoru; Haruki, Rie; Sakuraba, Yuya*; Yasuoka, Hiroshi; Takanashi, Koki; Saito, Eiji
Journal of Applied Physics, 109(7), p.073915_1 - 073915_4, 2011/04
Times Cited Count：19 Percentile：61.93(Physics, Applied)We present spin pumping using a Heusler alloy CoMnSi/Pt bilayer film. A spin current is produced by a ferromagnetic resonance (FMR) technique. The pure spin current injected into the Pt layer from the CoMnSi layer is detected by the inverse spin-Hall effect (ISHE), which converts the spin current into an electric current. We estimated a damping constant of the CoMnSi/Pt bilayer film from an angular dependence of FMR spectra. Using the damping constant efficiency of spin pumping from the CoMnSi layer is evaluated. We found that a mixing conductance at the CoMnSi/Pt interface is comparable to that at a permalloy/Pt interface.
MnSiChudo, Hiroyuki; Ando, Kazuya*; Saito, Kesami*; Okayasu, Satoru; Haruki, Rie; Sakuraba, Yuya*; Yasuoka, Hiroshi; Takanashi, Koki; Saito, Eiji
no journal, ,
no abstracts in English
Entani, Shiro; Matsumoto, Yoshihiro; Otomo, Manabu; Sakuraba, Yuya*; Avramov, P.; Naramoto, Hiroshi*; Takanashi, Koki; Sakai, Seiji
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MnSi using spin-polarized positron annihilationKawasuso, Atsuo; Sakuraba, Yuya*; Fukaya, Yuki; Zhang, H.; Maekawa, Masaki; Mochizuki, Izumi; Takanashi, Koki*
no journal, ,
We are attempting to determine the spin-polarization of the Heusler alloys using spin-polarized positron annihilation spectroscopy. Positrons implanted near the surface combine with electrons to form positronium (Ps). From the o-Ps (spin triplet state) fraction, one can determine the electron spin-polarization. The samples used in this study are CoMnSi films grown on MgO(001) substrates. To avoid the surface oxidation, the sample surfaces are capped with Au thin layers (0.5 nm thick). The electron polarization are obtained to be 0.26. This is significantly smaller than that determined by using the Andreev reflection method. The further study using samples without any cap layers are needed.
Sakai, Seiji; Matsumoto, Yoshihiro; Entani, Shiro; Otomo, Manabu; Sorokin, B. P.*; Avramov, P.; Naramoto, Hiroshi*; Sakuraba, Yuya*; Takanashi, Koki
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no abstracts in English
Kawasuso, Atsuo; Sakuraba, Yuya*; Zhang, H.; Maekawa, Masaki; Fukaya, Yuki; Takanashi, Koki*
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no abstracts in English
Kawasuso, Atsuo; Maekawa, Masaki; Fukaya, Yuki; Sakuraba, Yuya*; Saito, Eiji; Takanashi, Koki*
no journal, ,
Spin-polarized positron annihilation spectroscopy can be used for the studies of ferromagnetic electron momentum distribution and topmost surface electron spins. From this viewpoint, we argue the possibility of spin-polarized positron annihilation spectroscopy as a probe for spintronics materials. In the presentation, we introduce the theoretical formulation of the spin-polarized positron annihilation spectroscopy with some examples on classical ferromagnets, the latest results on the current-induced spin polarization, and some hopes to the first principles calculation to assist experiments.
MnGa filmsSumida, Kazuki; Sakuraba, Yuya*; Masuda, Keisuke*; Kono, Takashi*; Kakoki, Masaaki*; Goto, Kazuki*; Zhou, W.*; Miyamoto, Koji*; Miura, Yoshio*; Okuda, Taichi*; et al.
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no abstracts in English
MnGa filmsSumida, Kazuki; Sakuraba, Yuya*; Masuda, Keisuke*; Kono, Takashi*; Kakoki, Masaaki*; Goto, Kazuki*; Zhou, W.*; Miyamoto, Koji*; Miura, Yoshio*; Okuda, Taichi*; et al.
no journal, ,
no abstracts in English
MnGa filmsSumida, Kazuki; Sakuraba, Yuya*; Masuda, Keisuke*; Kono, Takashi*; Kakoki, Masaaki*; Goto, Kazuki*; Zhou, W.*; Miyamoto, Koji*; Miura, Yoshio*; Okuda, Taichi*; et al.
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no abstracts in English
MnSi Heusler alloy filmsSumida, Kazuki; Kakoki, Masaaki*; Sakuraba, Yuya*; Masuda, Keisuke*; Kono, Takashi*; Goto, Kazuki*; Miyamoto, Koji*; Miura, Yoshio*; Hono, Kazuhiro*; Okuda, Taichi*; et al.
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no abstracts in English
Mn(Al,Si) thin filmsSumida, Kazuki; Kakoki, Masaaki*; Sakuraba, Yuya*; Kono, Takashi*; Goto, Kazuki*; Miyamoto, Koji*; Hono, Kazuhiro*; Okuda, Taichi*; Kimura, Akio*
no journal, ,
no abstracts in English
MnSi filmsSumida, Kazuki; Kakoki, Masaaki*; Sakuraba, Yuya*; Masuda, Keisuke*; Kono, Takashi*; Goto, Kazuki*; Miyamoto, Koji*; Miura, Yoshio*; Hono, Kazuhiro*; Okuda, Taichi*; et al.
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