研究者業績
  1. 研究者検索結果一覧
  2. 和達 大樹

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

研究分野

 1

経歴

 6
もっとみる

学歴

 1

委員歴

 10
もっとみる

受賞

 7
もっとみる

論文

 202
  • Hiroki Wadati
    Physical Review B 2004年4月5日  
  • K. Okazaki, H. Wadati, A. Fujimori, M. Onoda, Y. Muraoka, Z. Hiroi
    Physical Review B - Condensed Matter and Materials Physics 69(16) 1-165104 2004年4月  査読有り
    We have made a detailed temperature-dependent photoemission study of VO2/TiO2(001) thin films, which show a metal-insulator transition at ∼300 K. Clean surfaces were obtained by annealing the films in an oxygen atmosphere. Spectral weight transfer between the coherent and incoherent parts accompanying the metal-insulator transition was clearly observed. We also observed a hysteretic behavior of the spectra for heating-cooling cycles. We have derived the "bulk" spectrum of the metallic phase and found that it has a strong incoherent part. The width of the coherent part is comparable to that given by band-structure calculation in spite of its reduced spectral weight, indicating that the momentum dependence of the self-energy is significant. This is attributed to by ferromagnetic fluctuation arising from Hund's rule coupling between different d orbitals as originally proposed by Zylbersztejn and Mott. In the insulating phase, the width of the V 3d band shows strong temperature dependence. We attribute this to electron-phonon interaction and have reproduced it using the independent boson model with a very large coupling constant.

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  
もっとみる

講演・口頭発表等

 34
もっとみる

担当経験のある科目(授業)

 14
もっとみる

所属学協会

 5

共同研究・競争的資金等の研究課題

 27
もっとみる

メディア報道

 13
もっとみる
一覧へ戻る