Anomalous thermoelectric effect derived from strongly correlated electrons

• Project/Area Number: 25420723
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Inorganic materials/Physical properties
• Research Institution: National Institute for Materials Science
• Principal Investigator: Isobe Masaaki 国立研究開発法人物質・材料研究機構, 機能性材料研究拠点・強相関物質グループ, グループリーダー (10354309)
• Co-Investigator(Kenkyū-buntansha): 新井 正男 国立研究開発法人物質・材料研究機構, 国際ナノアーキテクトニクス研究拠点・材料特性理論グループ, 主席研究員 (40222723)
• Project Period (FY): 2013-04-01 – 2017-03-31
• Project Status: Completed (Fiscal Year 2016)
• Budget Amount: ¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000); Fiscal Year 2015: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2014: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2013: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: 熱電材料 / 遷移金属酸化物 / 強相関電子系 / 磁性 / 計算物理 / 遷移金属化合物

Outline of Final Research Achievements

We have studied thermoelectric properties and electronic structure of the novel cobalt oxide Ca1-xNaxCo2O4 (0<= x <= 0.6). The Na-substituted phases with x = 0.5 ~ 0.6 exhibit metallic behavior of transport properties with large thermoelectric power comparable to those in layered cobalt oxides. We found that the Ca1-xNaxCo2O4 metallic phases have 1-dimensional-like large Fermi surfaces on the Gamma-Y direction in the momentum space. Wilson ratio is estimated to be 2 ~ 3, which is moderately strong electronic correlation. Origin of the large thermoelectric power is discussed from the viewpoint of the band structure and the electronic correlation in the 3d electron system.

Research Products

• [Journal Article] Superconductivity in noncentrosymmetric SrAuSi3 (2016)
  • Author(s): Masaaki Isobe, Masao Arai, and Naoki Shirakawa
  • Journal Title: Physical Review B Volume: 93 Issue: 5
  • DOI: 10.1103/physrevb.93.054519
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Two-Magnon Scattering in Spin&#8211;Orbital Mott Insulator Ba2IrO4 (2016)
  • Author(s): Shunsuke Tsuda, Hirotaka Okabe, Masaaki Isobe, and Shinya Uji
  • Journal Title: Journal of the Physical Society of Japan Volume: 85 Issue: 2 Pages: 023703-023703
  • DOI: 10.7566/jpsj.85.023703
  • NAID: 210000133818
  • Peer Reviewed
• [Journal Article] Superconductivity and crystal structural origins of the metal-insulator transition in Ba6-xSrxNb10O30 tetragonal tungsten bronzes (2015)
  • Author(s): Taras Kolodiazhnyi, Hiroya Sakurai, Masaaki Isobe, Yoshitaka Matsushita, Scott Forbes, Yurij Mozharivskyj, Timothy J. S. Munsie, Graeme M. Luke, Mary Gurak, and David R. Clarke
  • Journal Title: Physical Review B Volume: 92 Issue: 21 Pages: 214508-214508
  • DOI: 10.1103/physrevb.92.214508
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] SrAuSi3: A Noncentrosymmetric Superconductor (2014)
  • Author(s): Masaaki Isobe, Hiroyuki Yoshida, Koji Kimoto, Masao Arai, Eiji Takayama-Muromachi
  • Journal Title: Chem. Mater. Volume: 26 Issue: 6 Pages: 2155-2165
  • DOI: 10.1021/cm500032u
  • Peer Reviewed / Open Access
• [Journal Article] The electronic structure of the high-symmetry perovskite iridate Ba2IrO4 (2014)
  • Author(s): S. Moser, L. Moreschini, A. Ebrahimi, B. Dalla Piazza, M. Isobe, H. Okabe, J. Akimitsu, V. V. Mazurenko, K. S. Kim, A. Bostwick, E. Rotenberg, J. Chang, H. M. Rønnow, M. Grioni
  • Journal Title: New J. Phys. Volume: 16 Issue: 1 Pages: 13008-1
  • DOI: 10.1088/1367-2630/16/1/013008
  • Peer Reviewed / Open Access
• [Journal Article] Orbital occupancies and the putative jeff = 1/2 ground state in Ba2IrO4: A combined oxygen K-edge XAS and RIXS study (2014)
  • Author(s): M. Moretti Sala, M. Rossi, S. Boseggia, J. Akimitsu, N. B. Brookes, M. Isobe, M. Minola, H. Okabe, H. M. Rønnow, L. Simonelli, D. F. McMorrow, and G. Monaco
  • Journal Title: Phys. Rev. B Volume: 89 Issue: 12
  • DOI: 10.1103/physrevb.89.121101
  • Peer Reviewed / Open Access
• [Journal Article] Bulk nature of layered perovskite iridates beyond the Mott scenario : An approach from a bulk- sensitive photoemission study (2014)
  • Author(s): A. Yamasaki, H. Fujiwara, M. Sing, A. Sekiyama, and S. Suga(最終著者他22名)
  • Journal Title: Phys. Rev. B Volume: 89 Issue: 12 Pages: 121111-121111
  • DOI: 10.1103/physrevb.89.121111
  • Peer Reviewed / Open Access
• [Journal Article] Spin-Orbit-Coupling-Induced jeff States in Perovskite Iridates Studied by Photoemission Spectroscopy (2014)
  • Author(s): A. YAMASAKI, O. KIRILMAZ, A. IRIZAWA, A. HIGASHIYA, T. MURO, H. FUJIWARA, F. PFAFF, P. SCHEIDERER, J. GABEL, M. SING, M. YABASHI, K. TAMASAKU, A. HLOSKOVSKYY, H. OKABE, H. YOSHIDA, M. ISOBE, J. AKIMITSU, W. DRUBE, T. ISHIKAWA, S. IMADA, A. SEKIYAMA, R. CLAESSEN, S. SUGA
  • Journal Title: JPS Conf. Proc. Volume: 3
  • DOI: 10.7566/jpscp.3.013001
  • Peer Reviewed / Open Access
• [Journal Article] Carrier doping effect for transport properties of a spin-orbit Mott insulator Ba2IrO4 (2013)
  • Author(s): H. Okabe, M. Isobe, E. Takayama- Muromachi, N. Takeshita, and J. Akimitsu
  • Journal Title: Phys. Rev. B Volume: 88 Issue: 7
  • DOI: 10.1103/physrevb.88.075137
  • Peer Reviewed
• [Journal Article] Partially disordered spin structure in Ag2CrO2 studied with mu+SR (2013)
  • Author(s): J. Sugiyama, H. Nozaki, K. Miwa, H. Yoshida, M. Isobe, K. Prsa, A. Amato, D. Andreica, and M. Mansson
  • Journal Title: Physical Review B Volume: 88 Issue: 18
  • DOI: 10.1103/physrevb.88.184417
  • Peer Reviewed
• [Journal Article] Direct observatioｎ and dynamics of spontaneous skyrmion-like magnetic domains in a ferromagnet (2013)
  • Author(s): M. Nagao, Y.-Gi So, H. Yoshida, M. Isobe, T. Hara, K. Ishizuka, and K. Kimoto
  • Journal Title: Nature Nanotechnology Volume: 8 Issue: 5 Pages: 325-328
  • DOI: 10.1038/nnano.2013.69
  • Peer Reviewed
• [Journal Article] McMorrow, Robustness of basal-plane antiferromagnetic order and the Jeff = 1/2 state in single-layer iridate spin-orbit Mott insulators (2013)
  • Author(s): S. Boseggia, R. Springell, H. C. Walker, Ch. Rüegg, H. Okabe, M. Isobe, R. S. Perry, S. P. Collins, D. F. McMorrow
  • Journal Title: Phys. Rev. Lett. Volume: 110 Issue: 11
  • DOI: 10.1103/physrevlett.110.117207
  • Peer Reviewed
• [Journal Article] Pressure-induced metal-insulator transition of the mott insulator Ba2IrO4 (2013)
  • Author(s): D. Orii, M. Sakata, A. Miyake, K. Shimizu, H. Okabe, M. Isobe, E. Takayama-Muromachi, J. Akimitsu
  • Journal Title: Journal of the Korean Physical Society Volume: 63 Issue: 3 Pages: 349-351
  • DOI: 10.3938/jkps.63.349
  • Peer Reviewed
• [Journal Article] Magnetic States in Quasi-2-D Iridium Oxides with Large Spin-orbit Coupling (2013)
  • Author(s): M. Isobe, H. Okabe, J. Akimitsu
  • Journal Title: Journal of the Korean Physical Society Volume: 63 Issue: 3 Pages: 394-397
  • DOI: 10.3938/jkps.63.394
  • Peer Reviewed
• [Presentation] Magnetic and Transport Properties of the Spin-Orbit Mott Insulating Antiferromagnet Ba2IrO4 (2016)
  • Author(s): Masaaki Isobe
  • Organizer: EMN (Energy Materials Nanotechnology) Meeting on Magnetic Materials
  • Place of Presentation: Hawaii, USA
  • Year and Date: 2016-03-21
  • Int'l Joint Research / Invited
• [Presentation] Ba2IrO4: Spin-Orbit Mott State and its Carrier Doping Effect (2015)
  • Author(s): Masaaki Isobe
  • Organizer: EMN (Energy Materials Nanotechnology) Bangkok Meeting 2015
  • Place of Presentation: Bangkok, Thailand
  • Year and Date: 2015-11-10
  • Int'l Joint Research / Invited
• [Presentation] 対称中心を持たない新物質SrAuSi3の超伝導状態 (2015)
  • Author(s): 磯部雅朗，新井正男，室町英治
  • Organizer: 日本物理学会2015年秋季大会
  • Place of Presentation: 関西大学千里山キャンパス、大阪府吹田市
  • Year and Date: 2015-09-16
• [Presentation] Ba2IrO4: Carrier doping effect on the spin-orbit Mott state (2015)
  • Author(s): Masaaki Isobe
  • Organizer: EMN (Energy Materials Nanotechnology) Qingdao Meeting 2015
  • Place of Presentation: Qingdao, China
  • Year and Date: 2015-06-14
  • Int'l Joint Research / Invited
• [Presentation] 高圧合成の新物質Ag2FeO2とAg2CrO2の積層不整 (2014)
  • Author(s): 磯部雅朗・小野田みつ子・吉田紘行
  • Organizer: 平成26年度日本結晶学会年会
  • Place of Presentation: 東京大学、東京
  • Year and Date: 2014-11-01 – 2014-11-03
• [Presentation] 空間反転対称性の破れた超伝導体SrAuSi3の合成と物性 (2014)
  • Author(s): 磯部雅朗，木本浩司，新井正男，室町英治
  • Organizer: 日本物理学会2014年秋季大会
  • Place of Presentation: 中部大学、春日井市
  • Year and Date: 2014-09-07 – 2014-09-10
• [Presentation] A novel gold-based superconductor SrAuSi3 (2014)
  • Author(s): M. Isobe
  • Organizer: EMN (Energy Materials Nanotechnology) summer meeting 2014
  • Place of Presentation: The Westin Resort & Spa, Cancun, Mxico
  • Year and Date: 2014-06-09 – 2014-06-12
  • Invited
• [Presentation] 空間反転対称性の破れた新しい超伝導体SrAuSi3 (2014)
  • Author(s): 磯部雅朗、吉田紘行、木本浩司、新井正男、室町英治
  • Organizer: 日本物理学会第69回年次大会
  • Place of Presentation: 広島大学（東広島市）
• [Presentation] New-materials search for noncentrosymmetric superconductors (2013)
  • Author(s): Masaaki Isobe
  • Organizer: Mott Physics Beyond the Heisenberg Model (MPBH2013)
  • Place of Presentation: Centro Stefano Franscini - Swiss Federal Institute of Technology,Acsona,Switzerland
  • Invited
• [Presentation] Magnetic susceptibility of a spin-orbit Mott insulator Ba2IrO4 (2013)
  • Author(s): M. Isobe, H. Okabe, E. Takayama-Muromachi, and J. Akimitsu
  • Organizer: The Internal Conference on Strongly Correlated Electron Systems (SCES2013)
  • Place of Presentation: Ito International Research Center Conference, The University of ,Tokyo, Japan
• [Presentation] Magnetic properties of carrier-doped Ba2IrO4 probed by mSR (2013)
  • Author(s): H. Okabe, M. Isobe, E. Takayama-Muromachi, A. Koda, M. Hiraishi, M. Miyazaki, Y. Kadono, Y. Miyake, and J. Akimitsu
  • Organizer: The Internal Conference on Strongly Correlated Electron Systems (SCES2013)
  • Place of Presentation: Ito International Research Center Conference, The University of ,Tokyo, Japan
• [Presentation] Structural and transport properties of carrier-doped Ba2IrO4 (2013)
  • Author(s): H. Okabe, M. Isobe, E. Takayama-Muromachi, N. takeshita, and J. Akimitsu
  • Organizer: The Internal Conference on Strongly Correlated Electron Systems (SCES2013)
  • Place of Presentation: Ito International Research Center Conference, The University of ,Tokyo, Japan
• [Presentation] Doping effect on the Jeff = 1/2 Mott insulator Ba2IrO4 (2013)
  • Author(s): H. Okabe, M. Isobe, E. Takayama-Muromachi, N. Takeshita, A. koda, M. Hiraishi, M. Miyazaki. Y. Kadono, Y. Miyake, and J. Akimitsu
  • Organizer: International Workshop on Novel Superconductors and Super Materials
  • Place of Presentation: 品川グランドホール（東京）
• [Presentation] muSR study of the magnetic state in layered iridates (2013)
  • Author(s): H. Okabe, M. Isobe, E. Takayama-Muromachi, N. Takeshita, A. koda, M. Hiraishi, M. Miyazaki. Y. Kadono, Y. Miyake, and J. Akimitsu
  • Organizer: Light and Particle Beams in Materials Science 2013
  • Place of Presentation: つくば国際会議場（つくば市）
• [Presentation] YbB2C2の単結晶育成と物性評価 (2013)
  • Author(s): 岡部博孝、吉田紘行、磯部雅朗、松下能孝、佐藤晃、室町英治、秋光純
  • Organizer: 日本物理学会2013年秋期大会
  • Place of Presentation: 徳島大学常三島キャンパス（徳島市）
• [Presentation] 空間反転対称性の破れた超伝導体Ag2Pd3Sの物性 (2013)
  • Author(s): 吉田紘行、岡部博孝、松下能孝、室町英治、磯部雅朗
  • Organizer: 日本物理学会2013年秋期大会
  • Place of Presentation: 徳島大学常三島キャンパス（徳島市）