研究者詳細 - 伊藤　孝寛

論文 - 伊藤　孝寛

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Optical and photoelectrical studies on anisotropic metal-insulator transition of RuAs

Nakajima, Y; Mita, Z; Watanabe, H; Ohtsubo, Y; Ito, T; Kotegawa, H; Sugawara, H; Tou, H; Kimura, SI

PHYSICAL REVIEW B 100 巻 ( 12 ) 2019年9月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Physical Review B

The anisotropic changes in the electronic structure of a metal-to-insulator transition (MIT) material, RuAs, with a two-step phase transition are reported by using polarized optical conductivity σ(ω) spectra, angle-integrated photoelectron (PE) spectra, and band calculations based on the local-density approximation (LDA). Both the PE and σ(ω) spectra, not only in the high-temperature (HT) phase but also in the low-temperature (LT) phase as well as the energy gap formation owing to the MIT, were almost consistent with those derived from the LDA band calculations, so the fundamental electronic structure in the HT and LT phases can be explained without electron correlations. However, the electronic structure in the middle phase between the HT and LT phases has not been clarified. The polarized σ(ω) spectra revealed not only the anisotropic energy gap formation but also the anisotropic gap-opening temperature; that is, the energy gap along the c axis in the HT phase starts to open near the higher transition temperature, but that along the b axis opens below the lower transition temperature. The finding suggests that the two-step MIT originates from the anisotropic energy gap formation.

DOI： 10.1103/PhysRevB.100.125151

Web of Science

Scopus

Unified description of the electronic structure of M2AC nanolamellar carbides 査読有り

Pinek, D; Ito, T; Ikemoto, M; Yaji, K; Nakatake, M; Shin, S; Ouisse, T

PHYSICAL REVIEW B 100 巻 ( 7 ) 頁： 075144 1-13 2019年8月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Physical Review B

The nanolamellar M2AC or carbon-based "211 MAX" phases, where M is an early transition metal, A belongs to groups 13-15, and C is carbon, can be described by rigid band models. The same band model applies to all possible A elements belonging to a given group of the periodic table. Changing M for a given A is then equivalent to shifting the Fermi energy EF through a band structure common to all phases in the group. This is shown by comparing predictions of density functional theory (DFT) to angle-resolved photoemission spectroscopy (ARPES) measurements. In particular, the Fermi surface of a given Al-based MAX phase can be obtained with an acceptable degree of accuracy by simply selecting the appropriate ARPES isoenergy surface of another Al-based phase. In V2AlC, and in addition to conventional metal energy bands, both DFT and ARPES show the existence of a gapped nodal line located around 0.2 eV below EF or complex crossing points at EF with Dirac-like features in some directions. Application of the rigid band model suggests that these topological features as well as others, also predicted by DFT, can be positioned at or close to EF by an appropriate choice of M and A, or by using an appropriate combination of various M and A elements.

DOI： 10.1103/PhysRevB.100.075144

Web of Science

Scopus

名古屋大学大学院工学研究科　材料デザイン工学専攻　シンクロトロン光応用工学研究グループ

高嶋圭史, 伊藤孝寛

まてりあ 58 巻 ( 5 ) 頁： 276 - 277 2019年5月

Development of angle-resolved spectroscopy system of electrons emitted from a surface with negative electron affinity state 査読有り

Ichihashi Fumiaki, Dong Xinyu, Inoue Akito, Kawaguchi Takahiko, Kuwahara Makoto, Ito Takahiro, Harada Shunta, Tagawa Miho, Ujihara Toru

REVIEW OF SCIENTIFIC INSTRUMENTS 89 巻 ( 7 ) 頁： 073103 2018年7月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Review of Scientific Instruments

We developed an angle-resolved photoemission spectroscopy system for the analysis of conduction-band electrons. By forming a negative electron affinity surface on a semiconductor surface, electrons in conduction bands are emitted into a vacuum and measured by using an analyzer. This method enables us to determine the energy and momentum of the conduction electrons. Furthermore, it can be used to determine unoccupied conduction band structures. The main challenges of this method are that the energies of the emitted electrons are extremely low and the trajectories of the electrons change due to various influences. We overcame these problems by placing the shielding mesh close to the sample and parallel to the sample surface. The entire chambers, including the shielding mesh, were grounded, and a negative bias voltage was applied only to the sample. This configuration realizes the acceleration of electrons while preserving the momentum component parallel to the sample surface. Another problem is the establishment of a method for converting a detected angle into the corresponding wavevector. We focused on the emission angle of electrons emitted from a sample and their minimum energy and then established an analytical method for converting detected angles into corresponding wavevectors on the basis of the minimum energy.

DOI： 10.1063/1.5021116

Web of Science

Scopus

PubMed

RuAsの異方的金属絶縁体転移の光学的観測

中島裕喜, 木村真一, 三田善志郎, 日比滋元, 亀井俊, 渡邊浩, 小手川恒, 菅原仁, 藤秀樹, 伊藤孝寛

日本物理学会講演概要集 73 巻頁： 1043 - 1043 2018年

Temperature dependence of carrier relaxation time in gallium phosphide evaluated by photoemission measurements 査読有り

Ichihashi, F; Kawaguchi, T; Dong, XY; Kuwahara, M; Ito, T; Harada, S; Tagawa, M; Ujihara, T

AIP ADVANCES 7 巻 ( 11 ) 頁： 115314 2017年11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：AIP Advances

For understanding of carrier behavior in semiconductors, it is important to measure the carrier relaxation time. In the present study, the relaxation times of inter-valley transition from the Γ valley to the X valley in GaP were evaluated by near-band-gap photoemission spectroscopy of electrons emitted from a surface with a negative electron affinity state. In the energy distribution curves, two peaks, which originate from the electron population accumulated in the Γ valley and the X valley, were observed. From the temperature dependence of the energy of these two peaks, we could successfully evaluate the temperature dependence of the energies of the Γ valley and the X valley. Furthermore, the relaxation times of the inter-valley transition from the Γ valley to the X valley were estimated from the ratio of the electron concentration of the Γ valley and the X valley. The values of the relaxation time are good agreement with the previous studies. These results indicate that the near-band-gap photoemission spectroscopy can directly investigate conduction electrons and also evaluate the carrier dynamics in semiconductor.

DOI： 10.1063/1.4997800

Web of Science

Scopus

Synthesis of freestanding graphene on SiC by a rapid-cooling technique 査読有り

J. Bao, W. Norimatsu, H. Iwata, K. Matsuda, T. Ito, and M. Kusunoki

Physical Review Letters 117 巻頁： 20551 2016年11月

Band-like transport in highlycrystalline graphene films from defective graphene oxides 査読有り

R. Negishi, M. Akabori, T. Ito, Y. Watanabe, Y. Kobayashi

Scientific Reports 6 巻頁： 28936 2016年7月

Orbital-dependent electron correlation in LiFeAs revealed by angle-resolved photoemission spectroscopy 査読有り

T. Hajiri, T. Ito, M. Matsunami, B. H. Min, Y. S. Kwon, K. Kuroki and S. Kimura

PHYSICAL REVIEW B 93 巻頁： 024503 2016年6月

Origin of the black-golden transition in Sm1-xYxS 査読有り

K. Imura, T. Hajiri, M. Matsunami, S. Kimura, M. Kaneko, T. Ito, Y. Nishi, N. K. Sato, H. S. Suzuki

Journal of Physics: Conference Series. 592 巻頁： 012028 2015年3月

Fermi Surface Variation of Ce 4f-Electrons in Hybridization Controlled Heavy-Fermion Systems 査読有り

H.J. Im, T. Ito, H. Miyazaki, S. Kimura, Y.S. Kwon, Y. Saitoh, S.-I. Fujimori, A. Yasui, H. Yamagami

Solid State Communications 209-210 巻頁： 45-48 2015年3月

Anomalous Superconducting-Gap Structure of Slightly Overdoped Ba(Fe1-xCox)2As2 査読有り

T. Hajiri, T. Ito, M. Matsunami, B. H. Min, Y. S. Kwon, S. Kimura

83 巻頁： 093703 2014年8月

Angle-Resolved Photoemission Study on Insulator-to-Metal Transition of Sm1-xYxS 査読有り

M. Kaneko, M. Saito, T. Ito, K. Imura, T. Hajiri, M. Matsunami, S. Kimura, H. S. Suzuki, N. K. Sato

JPS Conference Proceedings 3 巻頁： 011080 1-6 2014年6月

Polarization-Dependent Three-Dimensional Angle-Resolved Photoemission Spectroscopy of BaFe1.8Co0.2As2 査読有り

T. Hajiri, T. Ito, M. Matsunami, B. H. Min, Y. S. Kwon, S. Kimura

JPS Conference Proceedings 3 巻頁： 015028 1-6 2014年6月

Spin-polarized angle-resolved photoelectron spectroscopy of the so-predicted Kondo topological insulator SmB6

S. Suga, K. Sakamoto, T. Okuda, K. Miyamoto, K. Kuroda, A. Sekiyama, J. Yamaguchi, H. Fujiwara, A. Irizawa, T. Ito, S. Kimura, T. Balashov, W. Wulfhekel, S. Yeo, F. Iga, S. Imada

J. Phys. Soc. Jpn. 83 巻頁： 014705 2013年12月

Three-Dimensional Angle-Resolved Photoemission Spectra of EuO Thin Film 査読有り

H. Miyazaki, H. Mitani, T. Hajiri, M. Matsunami, T. Ito, S. Kimura

J. Electron Spectrosc. Rel. Phenom. 191 巻頁： 7-10 2013年11月

Angle Resolved Photoemission Spectroscopy on Mixed-valence Sm1-xYxS

K. Imura, T. Hajiri, M. Matsunami, S. Kimura, M. Kaneko, T. Ito, Y. Nishi, N. K. Sato, H. S. Suzuki

J. Korean Phys. Soc. 62 巻頁： 2028-2032 2013年6月

Different evolution of intrinsic gap in strongly correlated SmB6 in contrast to YbB12

J. Yamaguchi, A. Sekiyama, M. Y. Kimura, H. Sugiyama, Y. Tomida, G. Funabashi, S. Komori, T. Balashov, W. Wulfhekel, T. Ito, S. Kimura, A. Higashiya, K. Tamasaku, M. Yabashi, T. Ishikawa, S. Yeo, S.-I. Lee, F. Iga, T. Takabatake, S. Suga

New Journal of Physics 15 巻頁： 043042 2013年4月

Polarization-dependent three-dimensional angle-resolved photoemission study on LiFeAs

T. Hajiri, R. Niwa, T. Ito, M. Matsunami, Y. J. Song, S. Kimura, Y. S. Kwon

Journal of Physics: Conference Series. 391 巻頁： 012125 2012年12月

Fabrication of single crystalline EuO thin films with SrO buffer layer on SrTiO3 substrate

H. Miyazaki, H. Momiyama, T. Hajiri, T. Ito, K. Imura, M. Matsunami, S. Kimura

Journal of Physics: Conference Series. 391 巻頁： 012047 2012年12月

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