研究者詳細 - 後藤　秀徳

論文 - 後藤　秀徳

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Semiconductor–metal transition in Bi2Se3 caused by impurity doping 査読

Takaki Uchiyama, Hidenori Goto, Eri Uesugi, Akihisa Takai, Lei Zhi, Akari Miura, Shino Hamao, Ritsuko Eguchi, Hiromi Ota, Kunihisa Sugimoto, Akihiko Fujiwara, Fumihiko Matsui, Koji Kimura, Kouichi Hayashi, Teppei Ueno, Kaya Kobayashi, Jun Akimitsu, Yoshihiro Kubozono

Scientific Reports 13 ( 1 ) 2023年1月

担当区分：責任著者掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

Abstract

Doping a typical topological insulator, Bi₂Se₃, with Ag impurity causes a semiconductor–metal (S-M) transition at 35 K. To deepen the understanding of this phenomenon, structural and transport properties of Ag-doped Bi₂Se₃ were studied. Single-crystal X-ray diffraction (SC-XRD) showed no structural transitions but slight shrinkage of the lattice, indicating no structural origin of the transition. To better understand electronic properties of Ag-doped Bi₂Se₃, extended analyses of Hall effect and electric-field effect were carried out. Hall effect measurements revealed that the reduction of resistance was accompanied by increases in not only carrier density but carrier mobility. The field-effect mobility is different for positive and negative gate voltages, indicating that the E_F is located at around the bottom of the bulk conduction band (BCB) and that the carrier mobility in the bulk is larger than that at the bottom surface at all temperatures. The pinning of the E_F at the BCB is found to be a key issue to induce the S-M transition, because the transition can be caused by depinning of the E_F or the crossover between the bulk and the top surface transport.

DOI： 10.1038/s41598-023-27701-5

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その他リンク： https://www.nature.com/articles/s41598-023-27701-5

Superconducting Behavior of BaTi₂(Sb_1–yBi_y)₂O under Pressure 査読国際共著

Mitsuki Ikeda, Ai Suzuki, Yanting Zhang, Hidenori Goto, Ritsuko Eguchi, Yen-Fa Liao, Hirofumi Ishii, Yoshihiro Kubozono

Inorganic Chemistry 61 ( 50 ) 20538 - 20546 2022年12月

Elucidation of the Local Structure of the Topological Insulator β-PdBi₂ by X-ray Fluorescence Holography 査読

Ai Suzuki, Yanting Zhang, Mitsuki Ikeda, Yuki Yamamoto, Ritsuko Eguchi, Hidenori Goto, Kaisei Yamamoto, Naohisa Happo, Koji Kimura, Kouichi Hayashi, Hirofumi Ishii, Yoshihiro Kubozono

The Journal of Physical Chemistry C 2022年12月

Charge Transport Capabilities of Dibenzo[n]phenacenes (n = 5–7): Influence of Trap States and Molecular Packing 査読

Yanting Zhang, Shino Hamao, Hidenori Goto, Yoshihiro Kubozono, Hideki Okamoto, Kunihisa Sugimoto, Nobuhiro Yasuda, Akihiko Fujiwara, Ritsuko Eguchi

The Journal of Physical Chemistry C 2022年10月

Superconducting Properties of Pd_1–xPt_xBi₂ over a Wide Pressure Range 査読

Ai Suzuki, Mitsuki Ikeda, Hirofumi Ishii, Yen-Fa Liao, Yasuhiro Takabayashi, Kouichi Hayashi, Hidenori Goto, Ritsuko Eguchi, Yoshihiro Kubozono

The Journal of Physical Chemistry C 126 ( 23 ) 9948 - 9955 2022年6月

Pressure dependence of superconductivity in alkali-Bi compounds KBi2 and RbBi2 査読

Huan Li, Mitsuki Ikeda, Ai Suzuki, Tomoya Taguchi, Yanting Zhang, Hidenori Goto, Ritsuko Eguchi, Yen-Fa Liao, Hirofumi Ishii, Yoshihiro Kubozono

PHYSICAL CHEMISTRY CHEMICAL PHYSICS 24 ( 12 ) 7185 - 7194 2022年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

The structural and superconducting properties of alkali-Bi-based compounds, KBi2 and RbBi2, were investigated over a wide pressure range for the first time. The samples of KBi2 and RbBi2 were prepared using a liquid ammonia (NH3) technique, and demonstrated superconductivity with superconducting transition temperatures, T-c, of 3.50 and 4.21 K at ambient pressure, respectively. The onset superconducting transition temperature, T-c(onset), of KBi2 decreased slightly; however, it suddenly jumped at 2 GPa and increased gradually with pressure, indicating the presence of two superconducting phases in the low-pressure range. The pressure-dependent X-ray diffraction patterns indicate that the KBi2 sample decomposed into KBi and Bi at pressures higher than 2.5 GPa. Moreover, a discontinuous change in T-c(onset) was observed for KBi2 at 9 GPa, which reflects the decomposition of KBi2 into KBi and Bi. By contrast, the value of T-c(onset) of RbBi2 was almost constant over a pressure range of 0-8 GPa. Thus, the superconducting properties and stability of alkali-Bi-based compounds against pressure were comprehensively explored in this study. In addition, the superconducting Cooper pair symmetry was investigated from the magnetic field dependence of T-c of KBi2 at 0.790 and 2.32 GPa, and of RbBi2 at 1.17 GPa, indicating the exact deviation from the simple s-wave paring model, which may be due to the complex electronic structure of Bi. The results elucidated the exotic superconducting properties of KBi2 and RbBi2 based on the pressure and magnetic field dependence of T-c and verified the chemical stability of KBi2 under pressure.

DOI： 10.1039/d2cp00679k

Web of Science

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Evaluation of Effective Field-Effect Mobility in Thin-Film and Single-Crystal Transistors for Revisiting Various Phenacene-Type Molecules 査読

Yanting Zhang, Ritsuko Eguchi, Shino Hamao, Hideki Okamoto, Hidenori Goto, Yoshihiro Kubozono

ACS OMEGA 7 ( 6 ) 2022年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

The magnitude of the field-effect mobility mu of organic thin-film and single-crystal field-effect transistors (FETs) has been over-estimated in certain recent studies. These reports set alarm bells ringing in the research field of organic electronics. Herein, we report a precise evaluation of the mu values using the effective field-effect mobility, mu(eff), a new indicator that is recently designed to prevent the FET performance of thin-film and single-crystal FETs based on various phenacene molecules from being overestimated. The transfer curves of a range of FETs based on phenacene are carefully categorized on the basis of a previous report. The exact evaluation of the value of mu(eff) depends on the exact classification of each transfer curve. The transfer curves of all our phenacene FETs could be successfully classified based on the method indicated in the aforementioned report, which made it possible to evaluate the exact value of mu(eff) for each FET. The FET performance based on the values of mu(eff) obtained in this study is discussed in detail. In particular, the mu(eff) values of single-crystal FETs are almost consistent with the mu values that were reported previously, but the mu(eff) values of thin-film FETs were much lower than those previously reported for mu, owing to a high absolute threshold voltage, vertical bar V-th vertical bar. The increase in the field-effect mobility as a function of the number of benzene rings, which was previously demonstrated based on the mu values of single-crystal FETs with phenacene molecules, is well reproduced from the mu(eff) values. The FET performance is discussed based on the newly evaluated mu(eff) values, and the future prospects of using phenacene molecules in FET devices are demonstrated.

DOI： 10.1021/acsomega.1c06932

Web of Science

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Fabrication and characterization of thin-film field-effect transistors with alkyl-phenyl[n]phenacenes (n = 4–6) 査読

Yanting Zhang, Ritsuko Eguchi, Hideki Okamoto, Kenta Goto, Fumito Tani, Minoru Yamaji, Hidenori Goto, Yoshihiro Kubozono

Journal of Materials Chemistry C 10 ( 43 ) 16309 - 16320 2022年

Superconductivity of topological insulator Sb2Te3−ySey under pressure 査読

Tomoya Taguchi, Mitsuki Ikeda, Huan Li, Ai Suzuki, Xiaofan Yang, Hirofumi Ishii, Yen-Fa Liao, Hiromi Ota, Hidenori Goto, Ritsuko Eguchi, Yoshihiro Kubozono

Journal of Physics: Condensed Matter 33 ( 48 ) 485704 - 485704 2021年9月

Superconducting properties of BaBi3 at ambient and high pressures 査読

Yanan Wang, Tomoya Taguchi, Huan Li, Ai Suzuki, Yanting Zhang, Akari Miura, Mitsuki Ikeda, Hidenori Goto, Ritsuko Eguchi, Takafumi Miyazaki, Yen-Fa Liao, Hirofumi Ishii, Yoshihiro Kubozono

Physical Chemistry Chemical Physics 23 ( 40 ) 23014 - 23023 2021年9月

Pressure Dependence of Superconducting Behavior of 4d and 5d Transition Metal Compounds CaRh2 and CaIr2 査読

Huan Li, Tomoya Taguchi, Yanan Wang, Hidenori Goto, Ritsuko Eguchi, Hirofumi Ishii, Yen-Fa Liao, Yoshihiro Kubozono

The Journal of Physical Chemistry C 125 ( 37 ) 20617 - 20625 2021年9月

Emergence of a Pressure-Driven Superconducting Phase in Ba0.77Na0.23Ti2Sb2O 査読

Tomoya Taguchi, Yanan Wang, Xiaofan Yang, Huan Li, Yasuhiro Takabayashi, Kouichi Hayashi, Takafumi Miyazaki, Yen-Fa Liao, Hirofumi Ishii, Hidenori Goto, Ritsuko Eguchi, Yoshihiro Kubozono

Inorganic Chemistry 60 ( 6 ) 3585 - 3592 2021年2月

Fabrication of ring oscillators using organic molecules of phenacene and perylenedicarboximide 査読

Niko Fioravanti, Luca Pierantoni, Davide Mencarelli, Claudio Turchetti, Shino Hamao, Hideki Okamoto, Hidenori Goto, Ritsuko Eguchi, Akihiko Fujiwara, Yoshihiro Kubozono

RSC Advances 11 ( 13 ) 7538 - 7551 2021年2月

Superconductivity in topological insulator β-PdBi2 under pressure 査読

Ai Suzuki, Tomoya Taguchi, Huan Li, Yanan Wang, Hirofumi Ishii, Yen-Fa Liao, Hidenori Goto, Ritsuko Eguchi, Yoshihiro Kubozono

Journal of Physics: Condensed Matter 33 ( 13 ) 135702 - 135702 2021年1月

Electronic structures of Bi2Se3 and AgxBi2Se3 under pressure studied by high-resolution x-ray absorption spectroscopy and density functional theory calculations 査読

Hitoshi Yamaoka, Harald O. Jeschke, Xiaofan Yang, Tong He, Hidenori Goto, Nozomu Hiraoka, Hirofumi Ishii, Jun'ichiro Mizuki, Yoshihiro Kubozono

Physical Review B 102 ( 15 ) 2020年10月

Superconducting behavior of BaTi2Bi2O and its pressure dependence 査読

Yanan Wang, Huan Li, Tomoya Taguchi, Ai Suzuki, Akari Miura, Hidenori Goto, Ritsuko Eguchi, Takafumi Miyazaki, Yen-Fa Liao, Hirofumi Ishii, Yoshihiro Kubozono

Physical Chemistry Chemical Physics 22 ( 40 ) 23315 - 23322 2020年10月

Superconductivity in Bi2−xSbxTe3−ySey (x = 1.0 and y = 2.0) under pressure 査読

Tong He, Xiaofan Yang, Tomoya Taguchi, Lei Zhi, Takafumi Miyazaki, Kaya Kobayashi, Jun Akimitsu, Hirofumi Ishii, Yen-Fa Liao, Hidenori Goto, Ritsuko Eguchi, Yoshihiro Kubozono

Journal of Physics: Condensed Matter 32 ( 46 ) 465702 - 465702 2020年8月

A new protocol for the preparation of superconducting KBi2 査読

Huan Li, Yanan Wang, Yutaro Aoki, Saki Nishiyama, Xiaofan Yang, Tomoya Taguchi, Akari Miura, Ai Suzuki, Lei Zhi, Hidenori Goto, Ritsuko Eguchi, Takashi Kambe, Yen-Fa Liao, Hirofumi Ishii, Yoshihiro Kubozono

RSC Advances 10 ( 45 ) 26686 - 26692 2020年7月

Structure and superconducting properties of multiple phases of (NH3)yAExFeSe (AE: Ca, Sr and Ba) 査読

Huan Li, Yanan Wang, Xiaofan Yang, Tomoya Taguchi, Lei Zhi, Hidenori Goto, Ritsuko Eguchi, Hirofumi Ishii, Yen-Fa Liao, Yoshihiro Kubozono

Journal of Physics: Condensed Matter 32 ( 39 ) 395704 - 395704 2020年6月

Inhomogeneous superconductivity in thin crystals of FeSe1−xTex (x=1.0, 0.95, and 0.9) 査読

Ritsuko Eguchi, Megumi Senda, Eri Uesugi, Hidenori Goto, Akihiko Fujiwara, Yasuhiko Imai, Shigeru Kimura, Takashi Noji, Yoji Koike, Yoshihiro Kubozono

Materials Research Express 7 ( 3 ) 036001 - 036001 2020年3月

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