研究者業績

和達 大樹

ワダチ ヒロキ  (Hiroki Wadati)

基本情報

所属
兵庫県立大学 大学院理学研究科 教授
学位
博士(理学)(東京大学)

研究者番号
00579972
ORCID ID
 https://orcid.org/0000-0001-5969-8624
J-GLOBAL ID
200901069788709054
researchmap会員ID
5000090682

外部リンク

研究キーワード

 2

委員歴

 10

論文

 202
  • S. Nakata, R. Takahashi, R. Matsumoto, L.-F. Zhang, H. Sumida, S. Suzuki, T. C. Fujita, M. Kawasaki, H. Wadati
    Applied Physics Letters 2024年5月13日  
  • Nao Komiyama, Takahiro Ohkubo, Yoshiki Maeda, Yuya Saeki, Nobuyuki Ichikuni, Hyuma Masu, Hirofumi Kanoh, Koji Ohara, Ryunosuke Takahashi, Hiroki Wadati, Hideaki Takagi, Yohei Miwa, Shoichi Kutsumizu, Keiki Kishikawa, Michinari Kohri
    Advanced Science 2024年3月13日  
  • Takuo Ohkochi, Ryunosuke Takahashi, Hidenori Fujiwara, Hirokazu Takahashi, Roman Adam, Umut Parlak, Kohei Yamamoto, Hitoshi Osawa, Masato Kotsugi, Arata Tsukamoto, Hiroki Wadati, Akira Sekiyama, Claus M. Schneider, Masakiyo Tsunoda, Shigemasa Suga, Toyohiko Kinoshita
    Journal of Magnetism and Magnetic Materials 171854-171854 2024年2月  
  • 和達 大樹, 山本 航平
    応用物理 92(10) 606-611 2023年10月  筆頭著者責任著者
  • Koki Uebo, Yuto Shiokawa, Ryunosuke Takahashi, Suguru Nakata, Hiroki Wadati
    F1000Research 12 860-860 2023年7月20日  最終著者責任著者
    <p>Background: Magneto-optical Kerr effect (MOKE) microscopes are powerful experimental tools to observe magnetic domains in magnetic materials. These devices are, however, typically large, unportable, and expensive (∼ several million yen), and therefore prevent many researchers in the field of materials science from easy access to study real-space images of magnetic domains.</p><p>Methods: To overcome these issues, we utilize data from ”The OpenFlexure Project” developed by the University of Bath and the University of Cambridge. The purpose of this project is to make high-precision mechanical positioning of the studied sample available to anyone with a 3D printer, especially for use in microscopes. We built a low-cost and portable MOKE microscope device by a 3D printer. We redesigned the 3D modeling data of an ordinary optical microscope provided by The OpenFlexure project and incorporated additional elements such as optical polarizers and an electro-magnetic coil into the primarily designed microscope that did not originally have these</p><p> elements.</p><p>Results: We successfully observed magnetic domains and their real-space motions induced by magnetic fields using the palm-sized low-cost MOKE microscope, which costs approximately 20,000 yen in raw materials to construct.</p><p>Conclusions: Our methodology to assemble a low-cost MOKE microscope will enable researchers working in the field of materials science to more easily observe magnetic domains without commercial equipment.</p>

MISC

 168
  • 鎌田知希, 森野喬, 下元直樹, 谷佳樹, 高橋龍之介, 和達大樹, 小阪田泰子, 藤塚守, 田原圭志朗, 小澤芳樹, 阿部正明
    錯体化学会討論会講演要旨集 73rd 2023年  
  • Kou Takubo, Huiyuan Man, Satoru Nakatsuji, Kohei Yamamoto, Yujun Zhang, Yasuyuki Hirata, Hiroki Wadati, Akira Yasui, Takashi Mizokawa, Daniel I. Khomskii
    Physical Review Materials 5(7) 2021年7月19日  
    Both the Jahn-Teller distortion of Cu$^{2+}$O$_6$ octahedra and magnetic ordering are absent in hexagonal Ba$_3$CuSb$_2$O$_9$ suggesting a Cu 3$d$ spin-orbital liquid state. Here, by means of resonant x-ray scattering and absorption experiment, we show that oxygen 2$p$ holes play crucial role in stabilizing this spin-orbital liquid state. These oxygen holes appear due to the "reaction" Sb$^{5+}$$\rightarrow$Sb$^{3+}$ $+$ two oxygen holes, with these holes being able to attach to Cu ions. The hexagonal phase with oxygen 2$p$ holes exhibits also a novel charge-orbital dynamics which is absent in the orthorhombic phase of Ba$_3$CuSb$_2$O$_9$ with Jahn-Teller distortion and Cu 3$d$ orbital order. The present work opens up a new avenue towards spin-charge-orbital entangled liquid state in transition-metal oxides with small or negative charge transfer energy.
  • Hiroshi Fukui, Hirokazu Kadobayashi, Hirotaka Abe, Ryunosuke Takahashi, Hiroki Wadati, Naohisa Hirao
    2021年4月22日  
    We have measured the lattice volume of ice VIII in different pressure-temperature pathways and found isothermal compression at low-temperature conditions makes the volume larger. Ice VIII has become its high-pressure phase with the molar volume of 6.45 cm^3 at 10 K where the pressure can be estimated as 60.4 GPa based on the third-order Birch-Murnaghan equation with parameters determined in this study (K_0= 32.4 GPa, K'_0= 3.7, and V_0= 11.9 cm^3). The present results indicate that this high-pressure state is paraelectric with tetragonal symmetry.
  • Kohei Yamamoto, Tomoyuki Tsuyama, Suguru Ito, Kou Takubo, Iwao Matsuda, Niko Pontius, Christian Schüßler-Langeheine, Makoto Minohara, Hiroshi Kumigashira, Yuichi Yamasaki, Hironori Nakao, Youichi Murakami, Takayoshi Katase, Toshio Kamiya, Hiroki Wadati
    NEW JOURNAL OF PHYSICS 24(4) 2021年3月30日  
    The relationship between the magnetic interaction and photoinduced dynamics in antiferromagnetic perovskites is investigated in this study. In La${}_{1/3}$Sr${}_{2/3}$FeO${}_{3}$ thin films, commensurate spin ordering is accompanied by charge disproportionation, whereas SrFeO${}_{3}$ thin films show incommensurate helical antiferromagnetic spin ordering due to increased ferromagnetic coupling compared to La${}_{1/3}$Sr${}_{2/3}$FeO${}_{3}$. To understand the photoinduced spin dynamics in these materials, we investigate the spin ordering through time-resolved resonant soft X-ray scattering. In La${}_{1/3}$Sr${}_{2/3}$FeO${}_{3}$, ultrafast quenching of the magnetic ordering within 130 fs through a nonthermal process is observed, triggered by charge transfer between the Fe atoms. We compare this to the photoinduced dynamics of the helical magnetic ordering of SrFeO${}_{3}$. We find that the change in the magnetic coupling through optically induced charge transfer can offer an even more efficient channel for spin-order manipulation.
  • 村主圭佑, 和達大樹, 新船幸二, 吉田晴彦, 堀田育志
    応用物理学会秋季学術講演会講演予稿集(CD-ROM) 82nd 2021年  

講演・口頭発表等

 34

担当経験のある科目(授業)

 14

共同研究・競争的資金等の研究課題

 27