Details of the Researcher

PHOTO

Toshiyuki Kodama
Section
Institute for Excellence in Higher Education
Job title
Specially Appointed Assistant Professor(Research)
Degree

  • 博士（理学）（奈良先端科学技術大学院大学）

  • 修士（理学）（奈良先端科学技術大学院大学）

Research History 3

  • 2022/04 - Present
    Tohoku University　Institute for Excellence in Higher Education　Project Assistant Professor

  • 2017/04 - 2022/03
    ナルックス株式会社

  • 2015/04 - 2017/03
    Japan Society for the Promotion of Science　SPS Research Fellowship for Young Scientist DC2

Education 3

  • Nara Institute of Science and Technology　Graduate School of Materials Science

    2014/04 - 2017/03

  • Nara Institute of Science and Technology　Graduate School of Materials Science

    2012/04 - 2014/03

  • Kobe University　Faculty of Engineering　Department of Electrical and Electronic Engineering

    2008/04 - 2012/03

Research Interests 5

  • 光物性

  • スピントロニクス

  • カイラリティ

  • 磁性

  • metamterial

Research Areas 2

  • Natural sciences / Semiconductors, optical and atomic physics /

  • Nanotechnology/Materials / Applied materials / metamaterial

Awards 5

  1. 基礎・材料・共通部門 優秀論文発表賞

    2023/09　一般社団法人電気学会　時間変調メタマテリアルに向けた透磁率変調

  2. Best Presentation Award

    2016/02　2016 Thailand-Japan Microwave　Nonreciprocal Microwave Transmission of a Magneto Chiral Metamolecule

  3. 奨励賞

    2014/02　応用物理学会関西支部平成25年度第3回講演会　強磁性金属カイラルメタ分子の作製とスピン波共鳴

  4. 最優秀ポスター賞

    2013/10　応用物理学会関西支部平成25年度第2回講演会　強磁性金属カイラルメタ分子の作製とスピン波共鳴

  5. NCTU Prize

    GIST/NAIST/NCTU joint symposium on advanced materials 2014　Spin-wave resonance in arrays of chiral meta-molecules of ferromagnetic-metal

Papers 16

  1. Microwave One-way Transparency by Large Synthetic Motion of Magnetochiral Polaritons in Metamolecules

    Kentaro Mita, Toshiyuki Kodama, Toshihiro Nakanishi, Tetsuya Ueda, Kei Sawada, Takahiro Chiba, Satoshi Tomita

    2025/03/28

    More details Close

    We observe microwave one-way transparency via ultrastrongly-coupled magnetochiral polaritons (MChPs) in a metamolecule with simultaneous breaking of time-reversal and space-inversion symmetries at room temperature. The experimental results are reproduced well via numerical simulations. Effective polarizability tensor analyses of the simulation results verify that the one-way transparency is traced back to massive synthetic motion of MChPs. This study paves a way to hybrid quantum systems and synthetic gauge fields using metamaterials.

  2. Magnetic Permeability Time-varying Metamaterials at Microwave Frequencies

    Toshiyuki Kodama, Nobuaki Kikuchi, Takahiro Chiba, Seigo Ohno, Satoshi Okamoto, Satoshi Tomita

    2025/03/06

    More details Close

    We demonstrate magnetic permeability time-varying metamaterials at GHz frequencies using ferromagnetic permalloy (Ni80Fe20; Py). We observe frequency up and down conversion of 4 GHz microwaves through the metamaterials, which is caused by the temporal modulation of permeability in the Py layer. Moreover, the efficiency of the up-conversion to a higher frequency is much larger than that of the down conversion to a lower frequency. These experimental results are reproduced well via numerical calculation, verifying that the significant up-conversion efficiency is traced back to nonlinear magnetization dynamics in the metamaterials. The present study opens a door to microwave sources toward the 6th-generation mobile communication system, four-dimensional metamaterials with spatio-temporal modulation, and nonlinear spintronics.

  3. Pure moving optical media consisting of magnetochiral metasurfaces Peer-reviewed

    Toshiyuki Kodama, Toshihiro Nakanishi, Kei Sawada, Satoshi Tomita

    Optical Materials Express　14　(11)　2499-2513　2024/11/01

    DOI： 10.1364/ome.535115 　

    ISSN： 2159-3930

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    <jats:p>We report on numerical studies of microwave bianisotropies by magnetochiral (MCh) metasurfaces consisting of double Z-type gammadions with perpendicularly magnetized substrates. The metasurfaces’ effective polarizability tensor, extracted from calculated reflection and transmission coefficients, has components of the non-reciprocal moving-type bianisotropy as well as the reciprocal chiral-type bianisotropy and non-reciprocal magneto-optical (MO) effect. The combination of the metasurfaces with contraposition MCh metasurfaces cancels both the chiral-type bianisotropy and MO effect, resulting in pure moving optical media. An achieved perfect transmission with a phase difference of <jats:italic toggle="yes">π</jats:italic> realizes an ideal gyrator for arbitrary spatial and polarization modes.</jats:p>

  4. Direct observation of current-induced nonlinear spin torque in Pt-Py bilayers Peer-reviewed

    Toshiyuki Kodama, Nobuaki Kikuchi, Takahiro Chiba, Satoshi Okamoto, Seigo Ohno, Satoshi Tomita

    Physical Review B　109　(21)　2024/06/13

    Publisher: American Physical Society (APS)

    DOI： 10.1103/physrevb.109.214419 　

    ISSN： 2469-9950

    eISSN： 2469-9969

  5. Fabrication and characterization of delay lines with spoof surface plasmon polariton waveguide coupled with C-shaped metamaterials for microwave integrated circuits Peer-reviewed

    Minh Van Nguyen, Nobuaki Kikuchi, Toshiyuki Kodama, Taiyu Okatani, Naoki Inomata, Yoshiaki Kanamori

    Japanese Journal of Applied Physics　2024/02/13

    Publisher: IOP Publishing

    DOI： 10.35848/1347-4065/ad2917 　

    ISSN： 0021-4922

    eISSN： 1347-4065

    More details Close

    Abstract Here, we proposed two delay lines consisting of spoof Surface Plasmon Polariton (sSPP) waveguides and C-shaped metamaterials (C-MMs). The delay lines, namely OFF and ON devices, were designed and fabricated. On the OFF device, an sSPP waveguide is capacitively coupled to the C-MMs via an air gap on a high-resistivity silicon substrate. On the ON device, a connection is established between the C-MMs and the sSPP waveguide by metal connectors. The difference in the electrical properties in the coupling between the C-MMs and the sSPP waveguide creates a large phase contrast between the ON and OFF delay lines. The structural design was performed using a numerical calculation based on a commercial finite element solver. We successfully fabricated and characterized delay lines with phase differences equal to tens of degrees between the ON and OFF devices in the target frequency range of 2-6 GHz, while maintaining the original transmittance properties. The promising applications of the delay lines are a phase shifter or modulator when integrating with suitable switches.

  6. 時間変調磁性メタマテリアルに向けたスピン流誘起透磁率変調の評価 Peer-reviewed

    児玉 俊之, 菊池 伸明, 岡本 聡, 大野 誠吾, 冨田 知志

    日本磁気学会論文特集号　8　(1)　15-23　2024/01

    DOI： 10.20819/msjtmsj.24TR810 　

  7. Spin-Current-Driven Permeability Variation for Time-Varying Magnetic Metamaterials Peer-reviewed

    Toshiyuki Kodama, Nobuaki Kikuchi, Satoshi Okamoto, Seigo Ohno, Satoshi Tomita

    Physical Review Applied　19　(4)　2023/04/26

    Publisher: American Physical Society (APS)

    DOI： 10.1103/physrevapplied.19.044080 　

    eISSN： 2331-7019

  8. Spin-current Driven Magnetic Meta-atoms for Time-varying Permeability

    Renya Shimizu, Toshiyuki Kodama, Nobuaki Kikuchi, Satohsi Okamoto, Seigo Ohno, Satoshi Tomita

    2023 IEEE International Magnetic Conference - Short Papers, INTERMAG Short Papers 2023 - Proceedings　2023

    DOI： 10.1109/INTERMAGShortPapers58606.2023.10228282 　

  9. Permeability Control of Ferromagnetic Wires for Time-varying Spintronic Metamaterials

    Toshiyuki Kodama, Nobuaki Kikuchi, Satoshi Okamoto, Seigo Ohno, Satoshi Tomita

    2023 IEEE International Magnetic Conference - Short Papers, INTERMAG Short Papers 2023 - Proceedings　2023

    DOI： 10.1109/INTERMAGShortPapers58606.2023.10228637 　

  10. Microwave Spectroscopy of a Single Permalloy Chiral Metamolecule on a Coplanar Waveguide Peer-reviewed

    Toshiyuki Kodama, Yusaku Kusanagi, Satoshi Okamoto, Nobuaki Kikuchi, Osamu Kitakami, Satoshi Tomita, Nobuyoshi Hosoito, Hisao Yanagi

    PHYSICAL REVIEW APPLIED　9　(5)　2018/05

    DOI： 10.1103/PhysRevApplied.9.054025 　

    ISSN： 2331-7019

  11. Enhanced magneto-optical Kerr effects in Py/Ag/Bi trilayers Peer-reviewed

    Patricia Riego, Satoshi Tomita, Kaoru Murakami, Toshiyuki Kodama, Nobuyoshi Hosoito, Hisao Yanagi, Andreas Berger

    JOURNAL OF PHYSICS D-APPLIED PHYSICS　50　(19)　2017/05

    DOI： 10.1088/1361-6463/aa69f9 　

    ISSN： 0022-3727

    eISSN： 1361-6463

  12. Ferromagnetic Resonance of a Single Magnetochiral Metamolecule of Permalloy Peer-reviewed

    Toshiyuki Kodama, Satoshi Tomita, Takeshi Kato, Daiki Oshima, Satoshi Iwata, Satoshi Okamoto, Nobuaki Kikuchi, Osamu Kitakami, Nobuyoshi Hosoito, Hisao Yanagi

    PHYSICAL REVIEW APPLIED　6　(2)　2016/08

    DOI： 10.1103/PhysRevApplied.6.024016 　

    ISSN： 2331-7019

  13. Fabrication and ferromagnetic resonance of cobalt chiral meta-molecule arrays Peer-reviewed

    Toshiyuki Kodama, Satoshi Tomita, Nobuyoshi Hosoito, Hisao Yanagi

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING　122　(1)　2016/01

    DOI： 10.1007/s00339-015-9564-7 　

    ISSN： 0947-8396

    eISSN： 1432-0630

  14. Lifetime reduction of a quantum emitter with quasiperiodic metamaterials Peer-reviewed

    Yuto Moritake, Kazuyuki Nakayama, Toshihiro Suzuki, Hiroyuki Kurosawa, Toshiyuki Kodama, Satoshi Tomita, Hisao Yanagi, Teruya Ishihara

    PHYSICAL REVIEW B　90　(7)　2014/08

    DOI： 10.1103/PhysRevB.90.075146 　

    ISSN： 2469-9950

    eISSN： 2469-9969

  15. Enhancement of upconversion luminescence of Er and Yb co-doped Y2O3 nanoparticle by Ag half-shell Peer-reviewed

    Toshiyuki Kodama, Minoru Fujii, Taishi Nakano, Kenji Imakita, Shinji Hayashi

    OPTICAL MATERIALS　35　(12)　2394-2399　2013/10

    DOI： 10.1016/j.optmat.2013.06.040 　

    ISSN： 0925-3467

    eISSN： 1873-1252

  16. Manipulation of spontaneous emission with quasi-periodic metamaterials Peer-reviewed

    K. Nakayama, Y. Moritake, T. Suzuki, H. Kurosawa, T. Kodama, S. Tomita, H. Yanagi, T. Ishihara

    Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest　2013

    DOI： 10.1109/CLEOPR.2013.6599960 　

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Misc. 8

  1. 時間変調メタマテリアルの研究開発

    冨田知志, 児玉俊之

    会報光触媒　76　24-31　2025/05

    Publisher: 光機能材料研究会

  2. Microwave Frequency Conversion using Time-varying Magnetic Metamaterials

    児玉俊之, 菊池伸明, 岡本聡, 岡本聡, 大野誠吾, 冨田知志, 冨田知志

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)　85th　2024

    ISSN： 2758-4704

  3. Ultrastrongly-coupled non-reciprocal magnon-polaritons in magnetochiral metamaterials

    冨田知志, 冨田知志, 三田健太郎, 児玉俊之, 上田哲也, 中西俊博, 澤田桂, 千葉貴裕, 千葉貴裕

    日本物理学会講演概要集(CD-ROM)　79　(2)　2024

    ISSN： 2189-079X

  4. Time-varying Permeability Metamaterials towards Microwave Frequency Conversion

    児玉俊之, 菊池伸明, 岡本聡, 岡本聡, 大野誠吾, 冨田知志, 冨田知志

    日本磁気学会学術講演概要集　48th　2024

    ISSN： 1882-2959

  5. Observation of electromagnon-polaritons in magneto-chiral meta-molecules

    三田健太郎, 児玉俊之, 上田哲也, 中西俊博, 澤田桂, 千葉貴裕, 千葉貴裕, 冨田知志, 冨田知志

    日本物理学会講演概要集(CD-ROM)　79　(2)　2024

    ISSN： 2189-079X

  6. メタマテリアル,メタサーフェス-微細構造と光の相互作用 時間変調磁性メタマテリアルの実現に向けて

    児玉俊之, 冨田知志

    光技術コンタクト　62　(6)　2024

    ISSN： 0913-7289

  7. Spin-current Induced Permeability Control of NiFe Wires towards Time-varying Metamaterials

    児玉俊之, 菊池伸明, 岡本聡, 岡本聡, 大野誠吾, 冨田知志, 冨田知志

    応用物理学会春季学術講演会講演予稿集(CD-ROM)　70th　2023

    ISSN： 2758-4704

  8. Permeability Control of Co Wires by Spin-current Injection for Time-varying Metamaterials

    清水蓮也, 児玉俊之, 菊池伸明, 岡本聡, 岡本聡, 大野誠吾, 冨田知志, 冨田知志

    応用物理学会春季学術講演会講演予稿集(CD-ROM)　70th　2023

    ISSN： 2758-4704

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Presentations 21

  1. Ultrastrongly coupled and directionally nonreciprocal magnon polaritons in magnetochiral metamolecules

    Kentaro Mita, Takahiro Chiba, Toshiyuki Kodama, Tetsuya Ueda, Toshihiro Nakanishi, Kei Sawada, Satoshi Tomita

    Physical Review Applied　2025/01/17

  2. Nonlinear Variation in Permeability Towards Time-varying Metamaterials

    T. Kodama, N. Kikuchi, T. Chiba, S. Okamoto, S. Ohno, S. Tomita

    Metamaterials 2024　2024/09/11

  3. Towards time-varying magnetic metamaterials Invited

    Toshiyuki Kodama, Nobuaki Kikuchi, Satoshi Okamoto, Seigo Ohno, Satoshi Tomita

    The 8th A3 Metamaterials Forum (2024)　2024/07/24

  4. Observation of Current-induced Nonlinear Spin Torque in Pt-Py Bilayers

    Toshiyuki Kodama, Nobuaki Kikuchi, Takahiro Chiba, Satoshi Okamoto, Seigo Ohno, Satoshi Tomita

    The 22nd International Conference on Magnetism (ICM2024)　2024/07/05

  5. Observation of ultrastrongly-coupled non-reciprocal magnon-polaritons in magnetochiral metamolecules

    冨田知志, 冨田知志, 三田健太郎, 児玉俊之, 上田哲也, 中西俊博, 澤田桂, 千葉貴裕, 千葉貴裕

    日本磁気学会学術講演概要集　2024

  6. Ultrastrongly-coupled non-reciprocal magnon-polaritons in magnetochiral metamaterials

    冨田知志, 冨田知志, 三田健太郎, 児玉俊之, 上田哲也, 中西俊博, 澤田桂, 千葉貴裕, 千葉貴裕

    日本物理学会講演概要集(CD-ROM)　2024

  7. Time-varying Permeability Metamaterials towards Microwave Frequency Conversion

    児玉俊之, 菊池伸明, 岡本聡, 岡本聡, 大野誠吾, 冨田知志, 冨田知志

    日本磁気学会学術講演概要集　2024

  8. Observation of electromagnon-polaritons in magneto-chiral meta-molecules

    三田健太郎, 児玉俊之, 上田哲也, 中西俊博, 澤田桂, 千葉貴裕, 千葉貴裕, 冨田知志, 冨田知志

    日本物理学会講演概要集(CD-ROM)　2024

  9. Permeability Control of Ferromagnetic Wires for Time-varying Spintronic Metamaterials

    T. Kodama, N. Kikuchi, S. Okamoto, S. Ohno, S. Tomita

    IEEE INTERMAG 2023　2023/05/18

  10. Spin-current Driven Permeability Variation for Time-varying Magnetic Metamaterials

    児玉俊之, 菊池伸明, 岡本聡, 岡本聡, 大野誠吾, 冨田知志, 冨田知志

    日本物理学会講演概要集(CD-ROM)　2023

  11. 時間変調メタマテリアルに向けたスピン流誘起透磁率制御

    児玉俊之, 菊池伸明, 岡本聡, 岡本聡, 大野誠吾, 冨田知志, 冨田知志

    電子情報通信学会技術研究報告(Web)　2023

  12. Spin-injection Induced Permeability Control for Time-varying Metamaterials

    児玉俊之, 清水蓮也, 菊池伸明, 岡本聡, 岡本聡, 大野誠吾, 冨田知志, 冨田知志

    日本磁気学会学術講演概要集　2023

  13. Nonlinear Effect of Spin-Torque Ferromagnetic Resonance in Py/Pt Bilayers

    児玉俊之, 菊池伸明, 千葉貴裕, 岡本聡, 岡本聡, 大野誠吾, 冨田知志, 冨田知志

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)　2023

  14. Magneto-chiral metasurfaces at microwave frequencies

    冨田知志, 冨田知志, 児玉俊之, 中西俊博, 澤田桂, 澤田桂

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)　2023

  15. Spin-current Induced Permeability Control of NiFe Wires towards Time-varying Metamaterials

    児玉俊之, 菊池伸明, 岡本聡, 岡本聡, 大野誠吾, 冨田知志, 冨田知志

    応用物理学会春季学術講演会講演予稿集(CD-ROM)　2023

  16. Permeability Control of Co Wires by Spin-current Injection for Time-varying Metamaterials

    清水蓮也, 児玉俊之, 菊池伸明, 岡本聡, 岡本聡, 大野誠吾, 冨田知志, 冨田知志

    応用物理学会春季学術講演会講演予稿集(CD-ROM)　2023

  17. Microwave Frequency Conversion Using Time-Varying Permeability Metamaterials

    児玉俊之, 黒澤裕之, 大野誠吾, 菊池伸明, 畑山正寿, 岡本聡, 岡本聡, 冨田知志, 冨田知志

    日本磁気学会学術講演概要集　2022

  18. Permeability Control of Magnetic Materials towards Time-varying Metamaterials

    児玉俊之, 黒澤裕之, 大野誠吾, 菊池伸明, 畑山正寿, 岡本聡, 岡本聡, 冨田知志, 冨田知志

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)　2022

  19. Permeability control for time-varying metamaterials

    児玉俊之, 黒澤裕之, 大野誠吾, 菊池伸明, 畑山正寿, 岡本聡, 岡本聡, 冨田知志, 冨田知志

    電気学会研究会資料(Web)　2022

  20. 磁気カイラルメタ分子の電気伝導特性 Invited

    児玉俊之, 冨田知志, 細糸信好, 柳久雄

    電子情報通信学会総合大会(2017)　2017/03/24

  21. Nonreciprocal microwave transmission through a single metamolecule with magnetism and chirality on coplanar waveguide

    T. Kodama, S. Okamoto, N. Kikuchi, O. Kitakami, S. Tomita, N. Hosoito, H. Yanagi

    Metamaterials 2016　2016/09/20

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Research Projects 3

  1. 人工フェリ/反強磁性メタ表面によるテラヘルツ光の非相反伝搬

    児玉 俊之

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 若手研究

    Institution: 東北大学

    2023/04/01 - 2026/03/31

  2. 金属カイラルメタ分子の作製と磁気共鳴に関する研究

    児玉 俊之

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 特別研究員奨励費

    Institution: 奈良先端科学技術大学院大学

    2015/04 - 2017/03

    More details Close

    平成２８年度は強磁性金属のマイクロコイル構造におけるマイクロ波応答の観測と電気伝導特性の評価を行った。 磁気カイラル効果の実験的観測のため、平行伝送線路を用いたマイクロ波分光を行った。同様の装置を用いて単一マイクロコイルでの信号を得ることには既に成功しているが、今回観測を目指す磁気カイラル効果の観測へ向けて、平行伝送線路のパターニングの改良と、平行伝送線路に平行に外部磁場を加える電磁石を新たに測定装置に組み込んだ。 測定の結果、我々の作製した強磁性金属マイクロコイルにおいて、マイクロ波の伝搬方向に依存した非相反性を示唆する結果が得られた。線路に対するマイクロコイルの位置に依存して、非相反性が出現することも明らかとなった。非相反性の主な原因としてエッジガイドモードによるものが考えられた。さらには磁気カイラル効果によるものと期待できる測定結果も得られた(T.Kodama et al., submitted.)。 これまでの電磁波における非相反性に加えて、電気伝導特性の評価を行った。これは電流に対する磁気カイラル効果が発現することを期待して行ったものである。ナノプローブを用いた４端子測定法を採用し、強磁性金属マイクロ構造に外部磁場を印加しながら測定を行った。電流電圧特性を評価したところ、磁場の方向またはコイルの巻き方向に依存した抵抗の変化が確認された。一方でその変化量は非常に小さく、電流に対する磁気カイラル効果の存在を積極的に主張するには至らなかった。原因としては外部磁場の印加方法や測定装置のノイズが挙げられる。今後改良を加えた測定が行われる予定である。

  3. Creation of synthetic gauge fields for light using magnetochiral metamaterials

    Tomita Satoshi, KODAMA Toshiyuki

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Nara Institute of Science and Technology

    2014/04 - 2017/03

    More details Close

    We studied electromagnetism in structured metamaterials with simultaneous time-reversal and space-inversion symmetry breaking by magnetism and chirality. Experimental direct observation of optical magnetochiral effects by a single metamolecule with magnetism and chirality was demonstrated at microwave frequencies. Numerical simulations reproduced well the experimental results and predicted the emergence of giant magnetochiral effects by combining resonances in the metamolecule. Microwave transmission patters through magnetochiral and chiral metamaterials were measured. Toward a higher frequency, the metamolecule was miniaturized in the presence of ferromagnetic resonance in a cavity and coplanar waveguide. Application of generalized magneto-optical ellipsometry for microwaves was studied. This work paves the way to the realization of synthetic gauge fields for electromagnetic waves, and to development of meta-condensed-matter physics using metamaterials.