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Kaya Kobayashi

Research Institute for Electronic Science　Material and Molecular SciencesProfessor

Researcher basic information

■ Degree
  • 博士(工学), 東京大学
■ URL
researchmap URLホームページURL■ Various IDs
Researcher ID
  • T-6258-2019
J-Global ID■ Research Keywords and Fields
Research Field
  • Nanotechnology/Materials, Applied physical properties
  • Natural Science, Magnetism, superconductivity and strongly correlated systems
  • Natural Science, Semiconductors, optical properties of condensed matter and atomic physics
■ Educational Organization

Career

■ Career
Career
  • Apr. 2024 - Present
    Hokkaido University, Research Institute for Electronic Science, Professor
  • Apr. 2016 - Mar. 2024
    Okayama University, The Research Institute for Interdisciplinary Science, Associate Professor
  • Apr. 2015 - Mar. 2016
    Okayama University, エネルギー環境新素材拠点, Associate Professor
Educational Background
  • The University of Tokyo, The Faculty of Engineering, Department of Applied Physics, Japan
  • The University of Tokyo, 工学系研究科, 物理工学専攻, Japan
Committee Memberships
  • Apr. 2023 - Mar. 2025
    日本物理学会, ダイバーシティ推進委員会 委員長, Society
  • Sep. 2024 - Sep. 2024
    日本物理学会, 現地実行委員, Society
  • Apr. 2021 - Mar. 2023
    日本物理学会, 第77期男女共同参画推進委員会委員, Society
  • Oct. 2013 - Sep. 2014
    日本物理学会領域７ 運営委員, Society
  • Mar. 2014
    応用物理学関係連合講演会 現地実行委員
  • Mar. 2007
    応用物理学関係連合講演会 現地実行委員, Society

Research activity information

■ Awards
  • 2014, PRL Editor's Suggestion
■ Papers
■ Other Activities and Achievements
■ Books and other publications
  • Superconductivity in carbides
    Kobayashi Kaya, 149-209
    Springer, Jul. 2019, [Joint work]
■ Lectures, oral presentations, etc.
  • Possible valence skipping superconductivity in doped Dirac metal
    Kaya Kobayashi; T. Ueno; T. Wakita; T. Furukawa; T. Itou; T. Yokoya
    Material Research Meeting 2019, 13 Dec. 2019, English, Invited oral presentation
    10 Dec. 2019 - 14 Dec. 2019, [Invited]
  • 量子極限近傍における角度依存磁気抵抗振動の量子効果
    日本物理学会第59回年次大会(日本物理学会), 2004
  • Quantum Features of Angular Dependent Magnetoresistance Oscillations in Q2D Conductors near High Magnetic Field Quantum Limet
    ICSM(ICSM2004), 2004
  • Study of Electronic Structure of Low Temperature Phase in K-(BEDーTTF)_2 KHg(SCN)_4 Using Angular Dependent Magnetoresistance Oscillations
    ISCOM(ISCOM2003), 2003
  • Electric Field Effect on Vertical Transport in Multilayer Systems under Tilted Magnetic Fields
    EP2DS(EP2DS15), 2003
  • 擬1次元導体の磁気抵抗効果における量子効果
    日本物理学会第58回年次大会(日本物理学会), 2003
  • Growth and Transport Measurement of (TMTSF)_2PF_6/(TMTSF)_2ClO_4
    ICSM(ICSM2002), 2002
  • 低次元導体の磁気抵抗角度効果の強電場効果
    日本物理学会秋季大会(日本物理学会), 2002
■ Syllabus
  • 電子物性物理学, 2024年, 修士課程, 理学院
  • 物理学外国語文献講読Ⅰ, 2024年, 学士課程, 理学部
  • 現代物理学特論, 2024年, 学士課程, 理学部
■ Affiliated academic society
  • Material Research Society
  • American Physical Society
  • 日本物理学会
■ Works
  • 微小電極を用いた微小低次元有機導体伝導測定法の確立（単独）
    Apr. 2007 - Mar. 2008
  • “Electric Field Effect on Vertical Magnetotransport in Multilays Systems under Tilted Magnetic Field”（Physica E(Elsevier)）
    200400
  • “Growth and Transport Measurement of (TMTSF)_2PF_6/(TMTSF)_2 ClO_4 Hetero-Junctions”（Synthetic Metals(Elsevier)）
    200300
■ Research Themes
  • Development of Archetypal Asymmetric Quantum Matters
    Grants-in-Aid for Scientific Research
    01 Apr. 2023 - 31 Mar. 2028
    大原 繁男; 松田 達磨; 小林 夏野; 清水 悠晴; 鬼丸 孝博
    Japan Society for the Promotion of Science, Grant-in-Aid for Transformative Research Areas (A), Nagoya Institute of Technology, 23H04870
  • Research Management of Unveiling, Design, and Development of Asymmetric Quantum Matters
    Grants-in-Aid for Scientific Research
    01 Apr. 2023 - 31 Mar. 2028
    鬼丸 孝博; 大槻 純也; 田端 千紘; 柳澤 達也; 大原 繁男; 吉田 紘行; 網塚 浩; 井澤 公一; 小林 達生; 小林 夏野; 木俣 基
    Japan Society for the Promotion of Science, Grant-in-Aid for Transformative Research Areas (A), Hiroshima University, 23H04866
  • Morphology control of PBA core-shell nanoparticles and the TEM observation of Nano-hetero surfaces
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Apr. 2020 - Mar. 2023
    糸井 充穂; 小松 徳太郎; 小林 夏野
    令和3年度はコアシェル型PBAのコアとなるサブミクロンサイズのKCoFeプルシアンブルー類似体粒子の高圧力下粉末X線構造解析を引き続き行った。解析から圧力誘起CTCSTは0.3GPaから0.4GPa付近（室温）で起こることを明らかにした。また、PBAは柔らかく、圧力をかけると構造がCubicからRhombohedralに変化すると言われていたが、100nm程のサイズのKCoFeでも同じような傾向が観測され、RbCoFeのデータと比べることができた。
    シェルとなる、NiCr-PBA(80nm程度のサンプルサイズ）を作成し、圧力下の物性を調べるため、NiCr-PBAの圧力下の磁化挙動を調べた。ZFCM（zero field cooled magnetization)、FCM (field cooled magnetization)、RM (remanent magnetization)測定から75Kの磁性転移を観測した。転移点付近でRMの磁化の値が負に反転する挙動が観測されため、交流磁化率測定を行い、NiCr-PBAの磁化率に周波数依存があることを確認した。またNiCr-PBAは圧力に敏感で0.3GPaほどかけると、転移温度は70Kに減少する。NiCr-PBAの磁気転移は圧力に敏感であるので、コアにCoFe-PBA、シェルにNiCr-PBAを接着させたコアシェル型PBAナノ粒子では、光や温度コントロールによるコアの体積変化に付随した構造の歪みは、コアシェル型PBA錯体の本来の物性に影響を与えると考えられる。
    CoFe-PBA＠NiCr-PBAのコアシェル型サンプルの低温TEM測定結果を解析し、NiCr-CoFeの接着面とCoFe格子を画像解析した。今後は画像解析と圧力依存性のデータをもとにコアシェル型PBAの歪が物性に与える影響を定量的に求める。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Nihon University, Coinvestigator, 20K05272
  • Establishment of a New Magnetoelectric Phenomenon - Current-Induced Magnetization
    Grants-in-Aid for Scientific Research
    01 Apr. 2019 - 31 Mar. 2022
    Itou Tetsuaki
    Although the "electric field"-induced magnetization effect has been widely discussed in the past, there has been little discussion or experimental demonstration of the "electric current"-induced magnetization effect. In this research project, we i) provided general symmetry consideration to discuss the "electric current"-induced magnetization, ii) selected candidate materials and presented experimental evidence of the current-induced magnetization by NMR measurements under pulsed electric current, and iii) clarified the underlying mechanism of the current-induced magnetization by first-principles band calculations. From these results, we succeeded in demonstrating the current-induced magnetization effect in bulk materials and clarifying the detailed conditions to realize the effect.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Tokyo University of Science, 19H01852
  • Valence-skip mechanism of superconductivity in doped Dirac electron system
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    01 Apr. 2018 - 31 Mar. 2021
    Kobayashi Kaya
    We study cubic superconductor Ag1-xSn1+xSe2 for its possible Dirac electrons in superconductivity and for its uniqueness being a valence skipping superconductor candidate. The synthesis of single crystals and polycrystalline crystals of wide variety are performed and confirmed that superconducting transition temperatures, Tcs, vary depending on the ratio between Ag and Sn. Due to the discontinuous valence state changes of Sn, 2+ and 4+, charge dispropornation in spatial forms is expected. It is also expected to have two distinct Sn-Se distances, however, the observed electronic states in nuclear magnetic resonance (NMR) show only one state, while distinct two states observed in X-ray photoemission spectroscopy (XPS). The contradicting results suggests the valence skipping behavior in the superconductivity depend on the timescale and the two valence states overlap and distributed uniformly.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Okayama University, 18K03540
  • New magnetoelectric effect and nuclear spin manupulation in elemental tellurium
    Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    01 Apr. 2015 - 31 Mar. 2017
    Itou Tetsuaki
    The magnetoelectric effect (electric/magnetic stimulus generates magnetic/electric response) in bulk matter is of growing interest both fundamentally and technologically. This effect has been studied intensively in multiferroic materials. We have discovered a new class of bulk magnetoelectric phenomenon, which is fundamentally distinct from that in multiferroic materials. We have demonstrated experimentally that in elemental tellurium, bulk magnetization is induced parallel to an applied current, which is quite beyond classical electromagnetism and the current framework for magnetoelectricity in multiferroic materials.
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Tokyo University of Science, 15K13524
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