Current Affiliation Organization 【 display / non-display 】

Current Affiliation Organization 【 display / non-display 】

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Affiliated academic organizations 【 display / non-display 】

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Research Areas 【 display / non-display 】

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Thesis 【 display / non-display 】

• 新奇相転移化合物CeRu2Al10の置換効果による研究

  2011.03

Published Papers 【 display / non-display 】

Published Papers 【 display / non-display 】

• Author Correction: Fermionic order by disorder in a van der Waals antiferromagnet.

  Okuma R, Ueta D, Kuniyoshi S, Fujisawa Y, Smith B, Hsu CH, Inagaki Y, Si W, Kawae T, Lin H, Chuang FC, Masuda T, Kobayashi R, Okada Y

  Scientific reports ( Scientific Reports )  13 ( 1 ) 2956   2023.02 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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• Anomalous Magnetic Moment Direction under Magnetic Anisotropy Originated from Crystalline Electric Field in van der Waals Compounds CeTe₃ and CeTe₂Se

  Daichi Ueta, Riki Kobayashi, Hiroki Sawada, Yuki Iwata, Shin-ichiro Yano, Shingo Kuniyoshi, Yuita Fujisawa, Takatsugu Masuda, Yoshinori Okada, Shinichi Itoh

  Journal of the Physical Society of Japan ( Physical Society of Japan )  91 ( 9 )   2022.09 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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• Structural Properties of (Ti, Zr)(Mn, Cr)₂M[0.1] (M = None, Fe, Co, Ni, and Cu) Hydrogen Storage Alloys : Composition Distribution and Occupied Site of Doped Element

  Nakagawa T.

  MATERIALS TRANSACTIONS ( 公益社団法人 日本金属学会 )  62 ( 6 ) 899 - 904   2021.06

  Type of publication: Research paper (scientific journal)

  　View Summary

  <p>CO₂ tolerance of hydrogen storage alloys of AB₂-type (C14 Laves phase) Ti_0.515Zr_0.485Mn_1.2Cr_0.8<i>M</i>_0.1 (AB₂-M, <i>M</i> = none, Fe, Co, Ni, and Cu) depends on dopant <i>M</i>. Since our goal is to clarify this mechanism, we determined the elemental analysis using X-ray absorption spectroscopy (XAS), scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), and neutron powder diffraction (NPD) with Rietveld refinement in this study. As a result of XAS analysis, a strong evidence of all doped elements occupying B site in AB₂ was obtained. SEM-EDX showed inhomogeneous composition with vacancy in B site and linear correlation of Ti/Zr and Mn/Cr ratio. The peak width in XRD patterns of AB₂-M depends on the magnitude of homogeneity, therefore the Rietveld analysis using NPD patterns could not be well refined. Thus, homogeneity is not important but element of B site would be important for CO₂ tolerance as well as AB₅ type alloys.</p>

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• Fermionic order by disorder in a van der Waals antiferromagnet

  Okuma R.

  Scientific Reports ( Scientific Reports )  10 ( 1 ) 15311   2020.12 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  <jats:title>Abstract</jats:title> <jats:p>CeTe<jats:sub>3</jats:sub> is a unique platform to investigate the itinerant magnetism in a van der Waals (vdW) coupled metal. Despite chemical pressure being a promising route to boost quantum fluctuation in this system, a systematic study on the chemical pressure effect on Ce<jats:sup>3+</jats:sup>(4<jats:italic>f</jats:italic><jats:sup>1</jats:sup>) states is absent. Here, we report on the successful growth of a series of Se doped single crystals of CeTe<jats:sub>3</jats:sub>. We found a fluctuation driven exotic magnetic rotation from the usual easy-axis ordering to an unusual hard-axis ordering. Unlike in localized magnetic systems, near-critical magnetism can increase itinerancy hand-in-hand with enhancing fluctuation of magnetism. Thus, seemingly unstable hard-axis ordering emerges through kinetic energy gain, with the self-consistent observation of enhanced magnetic fluctuation (disorder). As far as we recognize, this order-by-disorder process in fermionic system is observed for the first time within vdW materials. Our finding opens a unique experimental platform for direct visualization of the rich quasiparticle Fermi surface deformation associated with the Fermionic order-by-disorder process. Also, the search for emergent exotic phases by further tuning of quantum fluctuation is suggested as a promising future challenge.</jats:p>

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• Neutron scattering study of Ce(Te_1-xSe_x)₃ with a van der Waals coupling

  Ueta Daichi, Kobayashi Riki, Yano Shin-ichiro, Okada Yoshinori

  Meeting Abstracts of the Physical Society of Japan ( The Physical Society of Japan )  75.1 ( 0 ) 1916 - 1916   2020

  Type of publication: Research paper (scientific journal)

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Books 【 display / non-display 】

Books 【 display / non-display 】

• Flow chemistry : integrated approaches for practical applications

  Luis S. V. (Santíago V.), García-Verdugo E. (Eduardo) ( Part: Single Author )

  Royal Society of Chemistry  2020

Grant-in-Aid for Scientific Research 【 display / non-display 】

Grant-in-Aid for Scientific Research 【 display / non-display 】

• Grant-in-Aid for Scientific Research(C)

  Project Year: 2021.04  -   

• Realization of Kondo Spin Liquid

  Grant-in-Aid for Scientific Research(C)

  Project Year: 2021.04  -  2024.03 

  Direct: 3,200,000 (YEN)  Overheads: 4,160,000 (YEN)  Total: 960,000 (YEN)

• Realization of Kondo Spin Liquid

  Grant-in-Aid for Scientific Research(C)

  Project Year: 2021.04  -  2024.03 

  Direct: 3,200,000 (YEN)  Overheads: 4,160,000 (YEN)  Total: 960,000 (YEN)

• Grant-in-Aid for Young Scientists(B)

  Project Year: 2017.04  -  2019.03 

  Direct: 3,200,000 (YEN)  Overheads: 960,000 (YEN)  Total: 4,160,000 (YEN)

• Realization of Kondo spin-liquid state and study of their physical properties

  Grant-in-Aid for Young Scientists(B)

  Project Year: 2017.04  -  2019.03 

  Investigator(s): KOBAYASHI Riki, Yano Shin-ichiro, Wang Chin-wei, Ueta Daichi, Okada Yoshinori, Nakahara Kenshiro, Chinen Koya, Shiomi Sarina, Kuwamori Taizan 

  Direct: 3,200,000 (YEN)  Overheads: 4,160,000 (YEN)  Total: 960,000 (YEN)

  　View Summary

  Ce5Si3 is the only one sample, the Ce2-site of which may have the singlet spin-dimer ground state in Ce intermetallic compounds with Shastry-Sutherland lattice. In this study, we planned to grow the single crystals of Ce5Si3 and its La doping system and performed neutron scattering, specific heat, and magnetization measurements under ambient/physical pressure by using these unique crystals. Based on the above plan, the following results were obtained. 1. we succeeded to grow the single crystals of Ce5Si3, Ce4LaSi3, La5Si3, and Ce5Ga2Ge that is the new isostructural compound. 2. we clarified that the only Ce1-site order antiferromagnetically in Ce5Si3 by neutron diffraction experiments. 3. we could not finish the pressure experiment at the planned time due to the experimental troubles. Now we have just started that experiment.

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