Ibaraki University's
College of Science
Department of Science (Physics Course)


IGA Fumitoshi

Other affiliation / position

  1. Frontier Research Center for Applied Atomic Sciences Vice president
  2. Graduate School of Science and Engineering Major in Quantum Beam Science Professor
  3. Institute for University Education and Student Support Department of Arts and Sciences 兼務教員


  1. 日本学術振興会 特別研究員DC 1987/04/01-1989/03/31
  2. 通商産業省(現経済産業省)工業技術院電子技術総合研究所 研究員 1989/04/01-1994/03/31
  3. 通商産業省 工業技術院電子技術総合研究所(現産業技術総合研究所) 主任研究員 1994/04/01-1996/03/31
  4. 通商産業省工業技術院に出向 超伝導開発プロジェクト担当 1995/04/01-1995/09/30
  5. 電子技術総合研究所 帰任 1995/10/01-1996/03/31
  6. 広島大学理学部物性学科 助教授 1996/04/01-1998/03/31
  7. 広島大学大学院先端物質科学研究科助教授 1998/04/01-2007/03/31
  8. 広島大学大学院先端物質科学研究科准教授 2007/04/01-2011/03/31
  9. 茨城大学理学部物理コース 理工学研究科理学専攻 教授 2011/04/01-Present
  10. フロンティア応用原子科学研究センター 副センター長 2015/04/01-Present
  11. 大学院理工学研究科 量子線科学専攻 物質量子科学コース 教授 2016/04/01-Present

Academic background

  1. Tohoku University Faculty of Science Department of Physics 1982/03 Graduated
  2. Tohoku University Graduate School, Division of Natural Science 物理学第2専攻 Doctor later 1989/03 Completed

Academic degrees

  1. 理学博士 Tohoku University 1989/03

Current state of research and teaching activities

・近藤半導体の超強磁場(100 T),超高圧下(100 GPa超)の物性研究で金属非金属転移を探索
・超高圧下合成(20 GPa超)で新規のホウ化物、酸化物を開発

Research Areas

  1. Physical Properties I
  2. Physical Properties II

Research keywords

  1. 磁性、強相関電子系、物質開発、超高圧合成

Subject of research

  1. トポロジカル近藤絶縁体の基礎研究(YbB12,SmB6) 強相関半導体の一種、近藤半導体が実はとポロジカル絶縁体であることを最近明らかにした。光電子分光により,表面の電子状態や,バルクの電子構造を観測した. 2015/04/01-Present

Proposed theme of joint or funded research

  1. 最大20GPaの高圧環境を利用した新素材開発 Wish to undertake joint research with industry and other organizations including private sector. Commisioned research,Joint research 産学連携他広く門戸を開けて,高圧環境を駆使した物質作成の場を提供する.
  2. 光集中加熱法による単結晶育成 Wish to undertake joint research with industry and other organizations including private sector. Commisioned research,Joint research 最高2800℃の高温空間を作れるクセノン四楕円炉を1997年に開発した.この装置は後に世界的に広がったが,その1号機は茨城大で原液で活躍している.この装置により,希土類ホウ化物の純良単結晶を育成しているが、いろんな金属化合物の結晶育成にも応用できることは実証済みである.アイデアを持ち込んでくれれば,その純良単結晶作りにトライしたい.


  1. 希土類ホウ化物の高圧合成 伊賀文俊 高圧力の科学と技術,vol.26, No.3 日本高圧力学会 2016/09/01
  2. 「物理データ事典」第4章 量子物性 18. 磁性 「18.3. 近藤物質」 Fumitoshi Iga 日本物理学会編集、朝倉書店 2006 強相関化合物の近藤物質の近藤温度の他、特徴的な温度をまとめた


  1. Research paper (scientific journal) Joint Spontaneous structural distortion of the metallic Shastry-Sutherland system DyB4 by quadrupole-spin-lattice coupling Sim, H, Lee, S, Hong, KP, Jeong, J., Zhang, J. R., Kamiyama, T., Adroja, D. T., Murray, C. A., Thompson, S. P., Iga, F., Ji, S, Khomskii, D., Park, Je-Geun Physical Review B American Physics Society (APS) 94/ 19, 195128(1-?) 2016/11/15 10.1103/PhysRevB.94.195128 DyB4 has a two-dimensional Shastry-Sutherland (Sh-S) lattice with strong Ising character of the Dy ions. Despite the intrinsic frustrations, it undergoes two successive transitions: a magnetic ordering at T-N = 20K and a quadrupole ordering at T-Q = 12.5K. From high-resolution neutron and synchrotron x-ray powder diffraction studies, we have obtained full structural information on this material in all phases and demonstrate that structural modifications occurring at quadrupolar transition lead to the lifting of frustrations inherent in the Sh-S model. Our paper thus provides a complete experimental picture of how the intrinsic frustration of the Sh-S lattice can be lifted by the coupling to quadrupole moments. We show that two other factors, i.e., strong spin-orbit coupling and long-range Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in metallic DyB4, play an important role in this behavior.
  2. Research paper (scientific journal) Joint Surface Kondo Effect and Non-Trivial Metallic State of the Kondo Insulator YbB12 K. Hagiwara, Y. Ohtsubo, M. Matsunami, S. Ideta, K. Tanaka, H. Miyazaki, J. Rault, P. Le Fèvre, F. Bertran, A.T.-Ibrahimi, R. Yukawa, M. Kobayashi , K. Horiba, H. Kumigashira, K. Sumida, T. Okuda , F. Iga, S. Kimura Nature Communications Nature 7, 12690(1-?) 2016/08/31 10.1038/ncomms12690 A synergistic effect between strong electron correlation and spin–orbit interaction has been theoretically predicted to realize new topological states of quantum matter on Kondoinsulators (KIs), so-called topological Kondo insulators (TKIs). One TKI candidate has been experimentally observed on the KI SmB6(001), and the origin of the surface states (SS) and the topological order of SmB6 has been actively discussed. Here, we show a metallic SS on the clean surface of another TKI candidate YbB12(001) using angle-resolved photoelectron spectroscopy. The SS shows temperature-dependent reconstruction corresponding to the Kondo effect observed for bulk states. Despite the low-temperature insulating bulk, the reconstructed SS with c–f hybridization is metallic, forming a closed Fermi contour surrounding G on the surface Brillouin zone and agreeing with the theoretically expected behaviour for SS on TKIs. These results demonstrate the temperature-dependent holistic reconstruction of two-dimensional states localized on KIs surface driven by the Kondo effect.
  3. Research paper (scientific journal) Joint Synchrotron Radiation Mossbauer Spectroscopy Using Sm-149 Nuclei S. Tsutsui, R. Masuda, Y. Kobayashi, Y. Yoda, K. Mizuuchi, Y. Shimizu, H. Hidaka, T. Yanagisawa, T H. Amitsuka, F. Iga, M. Seto JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN THE PHYSICAL SOCIETY OF JAPAN 85/ 8, 83704(1-?) 2016/08/15 10.7566/JPSJ.85.083704 Synchrotron radiation Sm-149 Mossbauer spectroscopy in the energy domain has successfully been carried out on Sm2O3, SmBe13, and SmB6. The isomer shift values were determined in these compounds to discuss their Sm valence state. We also investigated the time window effect on spectra, which is useful for measuring spectra with "high-energy-resolution". This effect makes it possible to discuss the frequency of valence fluctuation in Sm compounds as well as determine Sm valence state precisely using the Sm-149 Mossbauer effect. We discussed the fluctuation of the Sm valence in SmB6.
  4. Research paper (scientific journal) Joint Momentum microscopy of SmB6 single crystals with detailed surface characterization M. Ellguth, C. Tusche, F. Iga, S. Suga Philosophical Magazine 96/ 31(SI), 3284-3306 2016/04/29 10.1080/14786435.2016.1185185
  5. Research paper (scientific journal) Joint Hybridization gap formation in the Kondo insulator YbB12 observed using time-resolved photoemission spectroscopy M. Okawa, Y. Ishida, M. Takahashi, T. Shimada, F. Iga, T. Takabatake, T. Saitoh, and S. Shin Physical Review B 92, 161108(R) 2015/10/12 http://dx.doi.org/10.1103/PhysRevB.92.161108 A detailed low-energy electronic structure of a Kondo insulator YbB12 was revealed by a synergetic combination of ultra-high-resolution laser photoemission spectroscopy (PES) and time-resolved PES. The former confirmed a 25-meV pseudogap corresponding to the Kondo temperature of this material, and more importantly, it revealed that a 15-meV gap and a Kondo-peak feature developed below a crossover temperature of T∗∼110K. In harmony with this, the latter discovered a very long recombination time exceeding 100 ps below ∼T∗. This is a clear manifestation of photoexcited carriers due to the bottleneck in the recovery dynamics, which is interpreted as a developing hybridization gap of a hard gap.

Research presentations

  1. Oral presentation(general) Surface Kondo effect and non-trivial metallic state of the Kondo insulator YbB12 International Symposium of Quantum Beam Science at Ibaraki University 2016/11/20
  2. Oral presentation(general) Research on novel material development in Ibaraki University and collaboration study with other agencies International Symposium of Quantum Beam Science at Ibaraki University 2016/11/20
  3. Oral presentation(general) Walker Module高圧装置立ち上げと希土類ホウ化物の物性 第57回高圧討論会 2016/10/28
  4. Oral presentation(general) 分子線エピタキシー法を用いた希土類硼化物の作製と物性 日本物理学会2016年秋季大会 2016/09/16
  5. Poster presentation MBE法による希土類六硼化物の作製と評価 II 日本物理学会2016年秋季大会 2016/09/15

Alloted class

  1. 情報処理概論(情報リテラシー)
  2. Magnetism1
  3. Magnetism2
  4. Magnetism2
  5. Magnetism1

Memberships of academic societies

  1. 日本高圧力学会 2001/04-Present
  2. 日本磁気学会 1989/04-Present
  3. 日本物理学会 1982/04-Present

Committee Career

  1. 物性グループ 物性委員会幹事 2015/10/01-2017/09/30