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

  London cetre for Nanotechnology, University College London , Postdoctoral Researcher

• 2019.04

  -

  Present

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

Academic Background 【 Display / hide 】

Academic Background 【 Display / hide 】

• 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 】

• スピントロニクス、スピンダイナミクス、磁気相転移、音波、ナノテクノロジー

Research Themes 【 Display / hide 】

Research Themes 【 Display / hide 】

• Modulation of spintronics effects using magnetic phase transitions, 

  2019.04

  -

  Present

• Study on magnon-phonon coupling using sound wave, 

  2019.04

  -

  Present

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

  2014.04

  -

  Present

Papers 【 Display / hide 】

Papers 【 Display / hide 】

• Spatiotemporal visualization of a surface acoustic wave coupled to magnons across a submillimeter-long sample by pulsed laser interferometry

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

  Physical Review Applied （Physical Review Applied)  21 （ 4 ）  2024.04

  Research paper (scientific journal), Joint Work,  ISSN  2331-7019

  　View Summary

  Surface acoustic waves (SAWs) coupled to magnons have attracted much attention because they allow for the long-range transport of magnetic information that cannot be achieved by magnon alone. We employed pulsed laser interferometry to visualize the entire spatiotemporal dynamics of a SAW that travels on a nickel (Ni) thin film and is coupled to magnons. It was possible to trace the coupling-induced amplitude reduction and phase shift that occurs as the SAW propagates over a distance of 0.4 mm. The observed changes are consistent with results obtained from conventional radio-frequency transmission measurements, which probe the total SAW absorption due to magnon-phonon coupling. This result verifies that our method can accurately capture the spatiotemporal dynamics of a SAW coupled to magnons across the entire length of the sample. Additionally, we validated our time-resolved profiles by comparing them with theoretical results that take the echo wave due to reflection into account. The impact of the echo wave is significant even when it has propagated over a distance of the order of millimeters. Our imaging results highlight the visualization of the long-range propagation of the SAW coupled to magnons and offer more information about the surface vibration profiles in such devices.

  • Access to Document (DOI)

• Y₃Fe₅O₁₂ film with multi-domain epitaxy on single-crystalline LiNbO₃ substrate

  Yamanoi K, Hase K, Komori S, Taniyama T, Nozaki Y

  APL Materials （APL Materials)  12 （ 2 ）  2024.02

  Research paper (scientific journal), Joint Work, Lead author, Corresponding author, Accepted,  ISSN  2166-532X

  　View Summary

  Y3Fe5O12 is one of the magnetic insulators that can realize high-speed and low-power-consuming spintronics devices. However, it is hard to prepare a high-quality Y3Fe5O12 film via a conventional sputtering process owing to its low crystalline texture, which leads to a crucial increase in the Gilbert damping constant. Moreover, a single crystalline Gd3Ga5O12 substrate, whose lattice constant is well matched with Y3Fe5O12, is indispensable to improve the crystallinity of the Y3Fe5O12 film. In this article, we demonstrated an epitaxial growth of multiple domains for a 30-nm-thick Y3Fe5O12 film by means of magnetron sputtering on a single crystalline 128° Y-X LiNbO3 substrate , which has been widely utilized in surface acoustic wave devices. From the pole figure of x-ray diffraction, an oblique epitaxial growth of Y3Fe5O12(400) is successfully observed on the 128° Y-X LiNbO3 substrate after a high-temperature post-annealing. The saturation magnetization is equivalent to the value of the epitaxial Y3Fe5O12 film on the Gd3Ga5O12 substrate. The relatively low effective Gilbert damping constant of 0.0039 also supports the high crystalline texture of the Y3Fe5O12 film. The developed growth technique will pave the way for the application of the Y3Fe5O12 film on magneto-acoustic devices.

  • Access to Document (DOI)

• NiFe/Pt 2層膜の音響スピン注入の温度依存性

  山野井一人, 鳥羽竜生, 能崎幸雄

  電気学会研究会資料 23 （ 076 ）  2023.08

  Research paper (conference, symposium, etc.), Joint Work, Lead author

• A large modulation of spin pumping using magnetic phase transitions in single crystalline dysprosium

  Kazuto Yamanoi, Yuri Sakakibara, Junji Fujimoto, Mamoru Matsuo, Yukio Nozaki

  Applied Physics Express （IOP Publishing)  16 （ 6 ） 063004 - 063004 2023.06

  Research paper (scientific journal), Joint Work, Lead author, Corresponding author, Accepted,  ISSN  18820778

  　View Summary

  Abstract
  
  We report a large modulation of spin pumping using temperature-induced magnetic phase transitions in c-axis oriented single crystalline dysprosium (Dy). From the temperature variation of the magnetic susceptibility, transitions from paramagnetic (PM) to ferromagnetic (FM) phases via antiferromagnetic (AFM) phase are clearly observed in the Dy. Unlike polycrystalline Dy, the spin pumping of both PM- and AFM-Dy are strongly suppressed owing to the increased non-dissipative backflow of spin current by the long-range spin transport, although two orders of magnitude difference exist between FM- and AFM-phases.

  • Access to Document (DOI)

• Spin-torque generation using a compositional gradient at the interface between titanium and tungsten thin films

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

  Physical Review B （AMER PHYSICAL SOC)  107 （ 17 ）  2023.05

  Research paper (scientific journal), Joint Work, Accepted,  ISSN  24699950

  　View Summary

  We experimentally demonstrate spin-torque generation using a compositional gradient at the interface between titanium and tungsten thin films. The width of the compositional gradient interface (CGI) between films is varied from 1.4 to 2.0 nm via sputtering. Spin-torque ferromagnetic resonance is observed in the ferromagnetic Ni95Cu5 alloy fabricated on a Ti/W bilayer with the CGI. The positive spin torque increases with decreasing CGI width, but a negative spin torque is superimposed owing to the negative spin Hall effect in bulk tungsten. A structural undulation in the CGI eliminates this variation in positive spin torque. The CGI width dependence of the spin torque is associated with the generation of spin and/or orbital angular momentum flow at the CGI. Spin-torque generation using a CGI expands the range of material choice for magnetic nonvolatile memory applications.

  • 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 】

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

  K. Yamanoi, Y. Nozaki

  International conference on Magnetism 2024, 

  2024.06

  -

  2024.07

  , 

  Poster presentation

• Spinwave resonance excitation via magnetoelastic effect in ferromagnetic nickel films induced by higher-order surface acoustic wave

  K. Yamanoi, Y. Nozaki

  11th International Symposium on Metallic Multilayers (MML2023), 

  2023.07

  , 

  Poster presentation

• Modulation of spin transport in Dy film with different magnetic phases

  K. Yamanoi, Y. Nozaki

  7th International Conference on Advances in Functional Materials (AFM2023), 

  2023.01

  , 

  Oral presentation (general)

• Spin transport in sputtered Dysprosium films

  K. Yamanoi, Y. Nozaki

  24th International Colloquium on Magnetic Films and Surfaces (ICMFS-2022), 

  2022.07

  , 

  Poster presentation

• Study on Epitaxial growth of Y3Fe5O12 FILM on 128° Y-X LiNbO3 substrate

  K. Yamanoi, K. Hase, Y. Nozaki

  Magnetics and Optics Research International Symposium (MORIS)2022, 

  2022.05

  , 

  Poster presentation

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

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

• 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)

• スピンダイナミクスと熱スピン注入の融合によるワイヤレス・スピン流生成とその応用

  2016.04

  -

  2018.03

  日本学術振興会, 科学研究費助成事業 特別研究員奨励費, 特別研究員奨励費, No Setting

  　View Summary

  エレクトロニクスデバイスの更なる高性能化・高機能化の観点から、磁性体中のスピンの特性を積極的に活用したスピンデバイスが注目されている。スピンデバイスを動作させるうえで、最も重要な物理量はスピン角運動量の流れに対応するスピン流であるため、これまでに様々なスピン流の生成・制御手法が開発されている。近年、スピン流と熱との相互作用に進展があり、磁性体/非磁性体の接合界面に温度勾配を設けると熱を駆動力としたスピン流が生じることが分かってきた。更に、これまでの研究から磁性薄膜にマイクロ波を照射して磁化の共鳴歳差運動現象を誘起することで、磁性体を加熱できることを明らかとした。このことは、このマイクロ波による磁性体加熱効果を、磁性体/非磁性体複合構造に適用することで、ワイヤレスにスピン流を制御可能なため、新奇なワイヤレス・スピンデバイスの創生が期待される。
  本研究プロジェクトの最終年度である本年度は、昨年度までに得られた研究成果である、発熱効果の高い磁性体の探索、熱励起スピン流の評価手法の開発等を活用し、ワイヤレス・スピンデバイスで重要となる熱スピン注入技術の更なる高効率化を目指したので、下記に報告する。
  素子(A)磁性体/白金/基板と素子(B)白金/磁性体/基板の類似の構造を持つ2つの素子を作製し、白金へ注入されるスピン流量を比較した。その結果、素子(A) のスピン流の注入量は素子(B) と比較して、3 倍近く大きい結果が得られた。これは、磁性体で発生した熱が、試料A では白金を介して、基板に逃げるため、効果的な温度勾配が形成されるのに対して、試料B では、主に基板に逃げるため、白金に流入する熱が小さくなる。その結果、観測されたスピン流生成量に大きな差が生じたことが考えられる。今回得られた結果は、構造のみでスピン流生成量の増大が可能なため、多種多様なスピンデバイスへの応用が期待できる。

• 共鳴歳差運動を利用したワイヤレス・熱スピン注入技術の開発とエナジーハーベスティングデバイスへの応用

  2015

  公益財団法人・村田学術振興財団, 研究者海外派遣, No Setting

• スピンダイナミクスと熱スピン注入の融合によるワイヤレス・スピン流生成とその応用

  2014

  国立大学法人九州大学 ロバート・ファン/アントレプレナーシップ・センター（QREC), 第7回 アカデミックチャレンジ2014, No Setting

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 】

• 電気学会 令和5年(2023)優秀論文発表賞A(本部表彰)

  2023.09, 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3年(2021)優秀論文発表賞(A部門賞)

  山野井一人, 2021.09, 一般社団法人電気学会

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

• 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 】

• PHYSICS LABORATORIES 2

  2024

• PHYSICS LABORATORIES 1

  2024

• PHYSICS D

  2024

• LABORATORIES IN SCIENCE AND TECHNOLOGY

  2024

• PHYSICS LABORATORIES 2

  2023

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Courses Previously Taught 【 Display / hide 】

Courses Previously Taught 【 Display / hide 】

• PHYSICS D

  Keio University

  2024.04

  -

  2025.03

• LABORATORIES IN SCIENCE AND TECHNOLOGY

  Keio University

  2024.04

  -

  2025.03

• PHYSICS LABORATORIES 2

  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 】

• 2023.06

  -

  Present

  日本磁気学会 企画幹事

• 2023.04

  -

  Present

  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

• 2023

  -

  Present

  企画幹事, 日本磁気学会

• 2023

  -

  Present

  チーフオーガナイザ, 日本磁気学会サマースクール

• 2021.06

  -

  Present

  日本磁気学会 企画委員 , 日本磁気学会

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