Study of spin-lattice dynamics and transports in frustrated spinel oxides

• Project/Area Number: 26800174
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Condensed matter physics II
• Research Institution: Tohoku University
• Principal Investigator: Tomiyasu Keisuke 東北大学, 理学(系)研究科(研究院), 助教 (20350481)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000); Fiscal Year 2015: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2014: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
• Keywords: スピン分子 / フラストレーション / スピン格子結合 / スピン揺らぎ

Outline of Final Research Achievements

We carried on with the combination work of neutron scattering and ultrasound measurements on the frustrated spinel oxides with no magnetic order. In ZnFe2O4 without orbital degree of freedom, we observed a molecular spin excitation level at 10 meV (~ 100 K in energy). Elastic constant softens below 100 K, in which the thermal population of this level decreases. In MgV2O4 with orbital degree of freedom, the spin-orbital order vanishes by slightly excess Mg and molecular spin excitations were found. However, the energy structure is described as not a discrete level but a broad distribution from near zero to over 30 meV (~ 300 K in energy). The softening of elastic constant was confirmed below 150 K at least, which will be extended up to 300 K in principle in consideration of the spin excitation energy. Our studies experimentally show that the molecular spin excitations are accompanied with spin-lattice coupling and become source of anomalous phonon properties.

Research Products

• [Int'l Joint Research] NSRRC(台湾)
• [Int'l Joint Research] ORNL(米国)
• [Journal Article] Observation of all-in type tetrahedral displacements in nonmagnetic pyrochlore niobates (2016)
  • Author(s): S. Torigoe, Y. Ishimoto, Y. Aoishi, H. Murakawa, D. Matsumura, K. Yoshii, Y. Yoneda, Y. Nishihata, K. Kodama, K. Tomiyasu, K. Ikeda, H. Nakao, Y. Nogami, N. Ikeda, T. Otomo, and N. Hanasaki
  • Journal Title: Phys. Rev. B Volume: 93 Issue: 8 Pages: 085109-085109
  • DOI: 10.1103/physrevb.93.085109
  • Peer Reviewed
• [Journal Article] Development of Spin Correlations in the Geometrically Frustrated Triangular-Lattice Heisenberg Antiferromagnet CuCrO2 (2015)
  • Author(s): Ryoichi Kajimoto, Keisuke Tomiyasu, Kenji Nakajima, Seiko Ohira-Kawamura, Yasuhiro Inamura, and Tetsuji Okuda
  • Journal Title: Journal of the Physical Society of Japan Volume: 7884 Issue: 7 Pages: 074708-074708
  • DOI: 10.7566/jpsj.84.074708
  • NAID: 210000133629
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Acoustic study of dynamical molecular-spin state without magnetic phase transition in spin-frustrated ZnFe2O4 (2015)
  • Author(s): Tadataka Watanabe, Shota Takita, Keisuke Tomiyasu, and Kazuya Kamazawa
  • Journal Title: Physical Review B Volume: 92 Issue: 17 Pages: 174420-174420
  • DOI: 10.1103/physrevb.92.174420
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Estimation of Bonding Nature Using Diamagnetic Susceptibility (2015)
  • Author(s): K. Tomiyasu, T. Sato, and S. Orimo
  • Journal Title: Chemical Communications Volume: in press Issue: 41 Pages: 8691-8694
  • DOI: 10.1039/c5cc02351c
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] フラストレート磁性体のスピンダイナミックス -スピネル酸化物にひそむスピンの分子たち- (2015)
  • Author(s): 富安啓輔
  • Journal Title: Radioisotopes Volume: in press
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Spin-Orbit Fluctuations in Frustrated Heavy-Fermion Metal LiV2O4 (2014)
  • Author(s): K. Tomiyasu, K. Iwasa, H. Ueda, S. Niitaka, H. Takagi, S. Ohira-Kawamura, T. Kikuchi, Y. Inamura, K. Nakajima, and K. Yamada
  • Journal Title: Phys. Rev. Lett. Volume: 113 Issue: 23 Pages: 236402-236402
  • DOI: 10.1103/physrevlett.113.236402
  • Peer Reviewed
• [Presentation] Te6+置換による電子ドープLaCoO3系におけるスピン状態ブロッケード (2015)
  • Author(s): 富安啓輔，小山俊一，綿引正倫，佐藤美嘉，西原和貴，小野寺貢，岩佐和晃，野島勉，山崎裕一，中尾裕則，村上洋一
  • Organizer: 日本物理学会第70回年次大会
  • Place of Presentation: 早稲田大（東京）
  • Year and Date: 2015-03-21 – 2015-03-24
• [Presentation] Spin-state blockade in Te6+-substituted electron-doped LaCoO3 (2015)
  • Author(s): K. Tomiyasu, S. Koyama, M. Watahiki, M. Sato, K. Nishihara, M. Onodera, K. Iwasa, T. Nojima, Y. Yamasaki, H. Nakao, and Y. Murakami
  • Organizer: APS March Meeting
  • Place of Presentation: Henry B. Gonzalez Convention Center (San Antonio, USA)
  • Year and Date: 2015-03-01 – 2015-03-05
• [Presentation] スピンフラストレート系スピネルZnFe2O4の弾性異常 (2014)
  • Author(s): 滝田将太，富安啓輔，蒲沢和也，渡辺忠孝
  • Organizer: 日本物理学会秋季大会
  • Place of Presentation: 中部大（春日井市）
  • Year and Date: 2014-09-18 – 2014-09-21
• [Presentation] 重い電子を示すフラストレーション系LiV2O4におけるスピン揺らぎ (2014)
  • Author(s): 富安啓輔，岩佐和晃，植田浩明，新高誠司，高木英典，河村聖子，菊池龍弥，稲村泰弘、中島健次，山田和芳
  • Organizer: 日本物理学会秋季大会
  • Place of Presentation: 中部大（春日井市）
  • Year and Date: 2014-09-18 – 2014-09-21
• [Remarks] 東北大学大学院理学研究科物理学専攻
  • URL: http://www.phys.tohoku.ac.jp/research-fields/cme1/materials_structure/