KEIO RESEARCHERS INFORMATION SYSTEM

Other Affiliation 【 Display / hide 】

Other Affiliation 【 Display / hide 】

• 理学部・物理学科, 助教

Career 【 Display / hide 】

Career 【 Display / hide 】

• 2017.04

  -

  2018.03

  Faculty of Sciences Department of Physics, Kyushu University , Post-doctoral fellow

• 2018.04

  -

  2018.06

  九州大学　理学研究院物理学部門, 技術職員

• 2018.07

  -

  2019.03

  University College of London, London Centre for Nanotechnology,  Postdoctoral Research Associate

• 2019.04

  -

  Present

  Keio University, Faculty of Science and Technology Department of Physics, Assistant Professor

Academic Background 【 Display / hide 】

Academic Background 【 Display / hide 】

• 2008.04

  -

  2012.03

  Fukuoka University, 理学部, 応用物理学科

  University, Graduated, Other

• 2012.04

  -

  2014.03

  Fukuoka University, 理学研究科, 応用物理学専攻

  Graduate School, Completed, Master's course

• 2014.04

  -

  2017.03

  Kyushu University, 理学府, 物理学専攻

  Graduate School, Completed, Doctoral course

Academic Degrees 【 Display / hide 】

Academic Degrees 【 Display / hide 】

• Doctor of Science, Kyushu University, National Institution for Academic Degrees and University Evaluation, 2017.03

Research Areas 【 Display / hide 】

Research Areas 【 Display / hide 】

• Natural Science / Magnetism, superconductivity and strongly correlated systems (spintronics, spin dynamics, spin wave, )

Research Keywords 【 Display / hide 】

Research Keywords 【 Display / hide 】

• Spintronics, Spindynamics, Magnetic phase transition, acoustic wave, nano fabrication

Research Themes 【 Display / hide 】

Research Themes 【 Display / hide 】

• Study on magnon-phonon coupling using sound wave, 

  2019.04

  -

  Present

• Modulation of spintronics effects using magnetic phase transitions, 

  2019.04

  -

  Present

• Study on interplay between heat and spin dynamics in ferromagnetic metal, 

  2014.04

  -

  Present

Papers 【 Display / hide 】

Papers 【 Display / hide 】

• Enhancement of magnon-phonon coupling in ferromagnetic Co2FeSi alloy using the monostable-bistable magnetic transition

  Kazuto Yamanoi, Shinya Yamada, Kohei Hamaya, Yukio Nozaki

  Physical Review Applied 26 ( 3 )  2026.09

  Research paper (scientific journal), Accepted,  ISSN  2331-7019

  　View Summary

  Surface acoustic waves (SAWs) excite GHz phonons that resonantly hybridize with magnons in the ferromagnet. Reducing the SAW fundamental frequency compresses the overtone spacing, enabling quasicontinuous and broadband spectral access to magnon-phonon interactions. We observe an enhancement of the magnon-phonon interaction strength at the monostable-bistable transition of magnetization, evaluated from the normalized magnon-induced SAW absorption and attributed to increased magnetic susceptibility. This approach enables systematic mapping of magnon-phonon hybridization over wide frequency and magnetic-field ranges and supports tunable magnonic functionalities.

  • Access to Document (DOI)

• Chirality-induced spin selectivity in organic spin valves utilizing 1,1′-Bi-2-naphthol with and without AlOx insulating layers

  Kotaro Kashima, Mizuki Matsuzaka, Ryunosuke Miyamoto, Koki Terai, Takumi Ueda, Kazuto Yamanoi, Yukio Nozaki, Masayuki Suda, Hideo Kaiju

  APL Materials 14 ( 5 )  2026.05

  ISSN  2166-532X

  　View Summary

  Recently, chirality-induced spin selectivity (CISS) has been observed in chiral molecules and has become attractive for applications in magnetoresistance (MR) devices. In this study, we fabricate CISS-based organic spin valves (OSVs) consisting of the chiral molecule 1,1′-Bi-2-naphthol (BINOL), sandwiched between an Au electrode and Co/Pt layers with perpendicular magnetic anisotropy, with and without an AlO<inf>x</inf> layer. We successfully fabricated Au/R-(+)-BINOL/Co/Pt/Co/Pt/Cr (Au/R-(+)-BINOL/[Co/Pt]<inf>2</inf>) and Au/S-(−)-BINOL/[Co/Pt]<inf>2</inf> OSVs. These devices, which exhibit sharp interfaces, demonstrate clear CISS-based MR effects under a low magnetic field of ∼20 mT at room temperature. The MR curves of both Au/R-(+)-BINOL/[Co/Pt]<inf>2</inf> and Au/S-(−)-BINOL/[Co/Pt]<inf>2</inf> OSVs correspond well to the perpendicular magnetization curves of the [Co/Pt]<inf>2</inf> electrodes. The polarity of the resistance change also exhibits opposite behaviors in the two devices. This indicates that an MR effect based on CISS is successfully observed in the Au/BINOL/[Co/Pt]<inf>2</inf> OSVs. In addition, we fabricate Au/BINOL/AlO<inf>x</inf>/[Co/Pt]<inf>2</inf> OSVs, in which an AlO<inf>x</inf> layer is inserted. We find that inserting an AlO<inf>x</inf> layer at the molecule/Co interface decreases both the MR and signal-to-noise (S/N) ratios of the MR curves compared with those of devices without an AlO<inf>x</inf> layer. The results of this study can contribute to elucidating the mechanism of CISS and provide new insights into its effect for spintronic device applications.

  • Access to Document (DOI)

• Electric‐Field Control of Low Damping Constant in Epitaxial Co2FeSi/LiNbO3 Multiferroic Heterostructures

  Shinya Yamada, Takamasa Usami, Sachio Komori, Yoshio Miura, Kazuto Yamanoi, Yukio Nozaki, Tomoyasu Taniyama, Kohei Hamaya

  Advanced Science 12 ( 41 )  2025.11

  　View Summary

  To develop electric-field control of magnetization dynamics in a magnetic material for magnonic devices with low-energy power consumption operation, an epitaxial half-metallic Co<inf>2</inf>FeSi/LiNbO<inf>3</inf> multiferroic heterostructure is experimentally demonstrated. The epitaxial Co<inf>2</inf>FeSi/LiNbO<inf>3</inf> multiferroic heterostructure shows a low damping constant (α) of ∼0.006 and the value of α is decreased to ∼0.004 by applying an electric field. This means that the magnetization dynamics in an epitaxial half-metallic Co<inf>2</inf>FeSi layer can be controlled via the piezoelectric strain of LiNbO<inf>3</inf> through the magnetoelastic coupling. This study leads to a way toward the realization of magnonic devices with low-energy power consumption operation.

  • Access to Document (DOI)

• Nanometer-Thick Si/Al Gradient Materials for Spin Torque Generation

  Taisuke Horaguchi, Cong He, Zhenchao Wen, Hayato Nakayama, Tadakatsu Ohkubo, Seiji Mitani, Hiroaki Sukegawa, Junji Fujimoto, Kazuto Yamanoi, Mamoru Matsuo, Yukio Nozaki

  Science Advances 11 ( 19 )  2025.05

  Accepted

  　View Summary

  Green materials for efficient charge-to-spin conversion are desired for common spintronic applications. Recent studies have documented the efficient generation of spin torque using spin-orbit interactions (SOIs); however, SOI use relies on the employment of rare metals such as platinum. Here, we demonstrate that a nanometer-thick gradient from silicon to aluminum, which consists of readily available elements from earth resources, can produce a spin torque as large as that of platinum despite the weak SOI of these compositions. The spin torque efficiency can be improved by decreasing the thickness of the gradient, while a sharp interface was not found to increase the spin torque. Moreover, the electric conductivity of the gradient material can be up to twice as large as that of platinum, which provides a way to reduce Joule heating losses in spintronic devices.

  • Access to Document (DOI)

• Reversal of Spin‐Torque Polarity with Inverting Current Vorticity in Composition‐Graded Layer at the Ti/W Interface

  Hayato Nakayama, Taisuke Horaguchi, Jun Uzuhashi, Cong He, Hiroaki Sukegawa, Tadakatsu Ohkubo, Seiji Mitani, Kazuto Yamanoi, Yukio Nozaki

  Advanced Electronic Materials 11 ( 7 )  2025.05

  ISSN  2199-160X

  　View Summary

  While compositional gradient-induced spin-current generation is explored, its microscopic mechanisms remain poorly understood. Here, the contribution of polarity of compositional gradient on spin-current generation is explored. A nanoscale compositional gradient, formed by in situ atomic diffusion of ultrathin Ti and W layers, is introduced between 10-nm-thick W and Ti layers. Spin-torque ferromagnetic resonance in ferromagnetic Ni<inf>95</inf>Cu<inf>5</inf> deposited on this gradient reveals that a moderate compositional gradient suppresses negative spin torque from the spin Hall effect in W. In contrast, reversing the Ti/W stacking order, which inverts the gradient, suppresses positive spin torque from the orbital Hall effect in Ti. These findings suggest that the sign of spin torque is governed by the polarity of compositional gradient, providing a novel strategy for efficient spin-torque generation without relying on materials with strong spin or orbital Hall effect.

  • Access to Document (DOI)

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Papers, etc., Registered in KOARA 【 Display / hide 】

Papers, etc., Registered in KOARA 【 Display / hide 】

• Spin injection in antiferromagnet using spin vorticity coupling

  Yamanoi, Kazuto

  科学研究費補助金研究成果報告書 2020

• Development of thermo-spin energy conversion using surface acoustic wave

  Yamanoi, Kazuto

  学事振興資金研究成果実績報告書 (慶應義塾大学)  2019

Presentations 【 Display / hide 】

Presentations 【 Display / hide 】

• Acoustically Driven Magnon-Phonon Coupling in an Epitaxially Grown Co2FeSi Alloy

  Kazuto Yamanoi, Shinya Yamada, Kohei Hamaya, Yukio Nozaki

  [International presentation]  The 8th International Conference on Electronic Materials and Nanotechnology for Green Environment (ENGE2024), 

  2024.11

  , 

  Oral presentation (general)

• Comparison of temperature dependence of the acoustically excited spin waves between NiFe and NiFe/Pt films

  K. Yamanoi, Y. Nozaki

  [International presentation]  International conference on Magnetism 2024, 

  2024.06

  -

  2024.07

  , 

  Poster presentation

• Experimental demonstration of SOT switching in a Pt/Co/Pt trilayer film fabricated on a Si/Al gradient material

  S. Takagi, T. Horaguchi, K. Yamanoi, Y. Nozaki

  [International presentation]  International conference on Magnetism 2024, 

  2024.06

  -

  2024.07

  , 

  Poster presentation

• Direct imaging of spatial decay profiles of surface acoustic waves due to magnon-phonon coupling in ferromagnets

  K. Maezawa, S. Fujii, K. Yamanoi, Y. Nozaki, S. Watanabe

  [International presentation]  International conference on Magnetism 2024, 

  2024.06

  -

  2024.07

  , 

  Oral presentation (general)

• Spin torque modulation using compositional gradient interface between Ti and W

  H. Nakayama, T. Horaguchi, C. He, H. Sukegawa, T. Ohkubo, S. Mitani, K. Yamanoi, Y. Nozaki

  [International presentation]  International conference on Magnetism 2024, 

  2024.06

  -

  2024.07

  , 

  Poster presentation

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

Research Projects of Competitive Funds, etc. 【 Display / hide 】

• 金属ナノドットハニカム格子のバレー自由度を用いたスピンメカトロニクス

  2025.04

  -

  2028.03

  基盤研究(C), Principal investigator

• キメラ準粒子の高効率生成に向けたメタマテリアル共振器の開発

  2025.04

  -

  2027.03

  学術変革領域研究(A), Principal investigator

• 弾性波を用いた巨大スピンホール効果の起源解明と高効率化に関する研究

  2022

  -

  2023

  公益財団法人 村田学術振興, 公益財団法人 村田学術振興 研究助成, Other, No Setting

• Spin injection in antiferromagnet using spin vorticity coupling

  2019.08

  -

  2021.03

  MEXT,JSPS, Grant-in-Aid for Scientific Research, YAMANOI KAZUTO, Grant-in-Aid for Research Activity Start-up , Principal investigator

  　View Summary

  In this research, we have study a non-thermal spin injection in antiferromagnetic Dy using spin-vorticity coupling(SVC).
  (a)We succeeded the fabricate for a high-quality Dy film by optimizing the deposition conditions. (b)We demonstrated the non-linear change of the spin-pumping effect in a Dy/NiFe bi-layer using a temperature-induced magnetic phase transition of Dy.(c)Since the surface acoustic wave was suppressed by Dy film, the SVC could not be observed. As a solution to these problems, we succeeded in a thinner Dy film.

• 静水圧力による純スピン流制御

  2017

  QRプログラム・わかばチャレンジ, Coinvestigator(s)

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Intellectual Property Rights, etc. 【 Display / hide 】

Intellectual Property Rights, etc. 【 Display / hide 】

• スピントロニクス素子、ワイヤレス給電装置、磁気センサー、磁気記録媒体、磁気メモリ、高周波フィルタおよびスピン発振器

  Date applied： 特願2015-185269  2015.09 

  Date announced： 特開2016-066796  2016.04 

  Patent

Awards 【 Display / hide 】

Awards 【 Display / hide 】

• 学会活動貢献賞

  2025.07, 公益社団法人・日本磁気学会, 企画委員会活動を通した学会活動の活性化への貢献

• 電気学会 令和5年(2023)優秀論文発表賞A(本部表彰)

  2024.09, 一般社団法人電気学会

  Type of Award： Award from Japanese society, conference, symposium, etc.

• 電気学会 令和5年(2023)優秀論文発表賞A(本部表彰)

  山野井一人, 2024.09, 一般社団法人電気学会

• 電気学会 令和3年(2021)優秀論文発表賞(A部門賞)

  山野井一人, 2022.09, 一般社団法人電気学会

  Type of Award： Award from Japanese society, conference, symposium, etc.

• 日本磁気学会　桜井講演賞

  2016.09, 日本磁気学会, 強磁性共鳴による磁性体加熱効果と熱スピン注入

  Type of Award： Award from Japanese society, conference, symposium, etc.

Courses Taught 【 Display / hide 】

Courses Taught 【 Display / hide 】

• LITERATURE OF PHYSICS

  2026

• BACHELOR'S THESIS

  2026

• PHYSICS LABORATORIES 2

  2026

• PHYSICS LABORATORIES 1

  2026

• PHYSICS D

  2026

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Courses Previously Taught 【 Display / hide 】

Courses Previously Taught 【 Display / hide 】

• PHYSICS LABORATORIES 2

  Keio University

  2024.04

  -

  2025.03

• PHYSICS D

  Keio University

  2024.04

  -

  2025.03

• LABORATORIES IN SCIENCE AND TECHNOLOGY

  Keio University

  2024.04

  -

  2025.03

• PHYSICS LABORATORIES 1

  Keio University

  2024.04

  -

  2025.03

• PHYSICS D

  Keio University

  2023.04

  -

  2024.03

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Media Coverage 【 Display / hide 】

Media Coverage 【 Display / hide 】

• マイクロ波を用いた熱スピン注入技術の開発 －ワイヤレス・スピンデバイスの実現に期待－

  2017.12

• 小さな磁石の大きな可能性

  2016.08

Memberships in Academic Societies 【 Display / hide 】

Memberships in Academic Societies 【 Display / hide 】

• The Institute of Electrical Engineers of Japan, 

  2019.06

  -

  Present

• 日本磁気学会, 

  2016.04

  -

  Present

• 日本物理学会, 

  2013.04

  -

  Present

• 日本応用物理学会, 

  2013.04

  -

  Present

Committee Experiences 【 Display / hide 】

Committee Experiences 【 Display / hide 】

• 2025.07

  -

  Present

  電気学会 ナノスケール磁性体研究会技術調査専門委員 幹事, 電気学会 ナノスケール磁性体研究会技術調査専門委員

• 2025.06

  -

  Present

  日本磁気学会 総務委員, 日本磁気学会

• 2023.06

  -

  2025.06

  日本磁気学会 企画幹事, 日本磁気学会

• 2023.06

  -

  2025.06

  日本磁気学会サマースクール, チーフオーガナイザ , 日本磁気学会

• 2021.06

  -

  2025.06

  日本磁気学会 企画委員 , 日本磁気学会

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