2001 Fiscal Year Annual Research Report

軌道相転移の制御による新物質創製

Research Project

Project/Area Number	11220207
Research Institution	Aoyama Gakuin University
Principal Investigator	秋光純青山学院大学, 理工学部, 教授 (80013522)
Co-Investigator(Kenkyū-buntansha)	廣田和馬東北大学, 大学院・理学研究科, 助教授 (90272012) 有馬孝尚筑波大学, 物質工学系, 助教授 (90232066) 古川信夫青山学院大学, 理工学部, 助教授 (00238669)
Keywords	軌道整列 / マンガン酸化物 / 四重極秩序 / ペロブスカイト
Research Abstract	以下の4つのテーマについて、お互いに連絡をとりつつ研究を行った。 1)パイロクロア構造を持つLu_2V_2O_7について、その軌道整列を偏極中性子回折を用いて決定した。得られた結果は、各四面体構造の頂点にあるVの波動関数のローブの伸びる方向が<111>に向いているという結果を得た。さらにCeB_6という四重極秩序を持つ物質の軌道秩序を決定した。その中で特に強磁性的な磁気モーメントがB-Bの中間の位置に存在するという、大変予想外の結果を得た。 2)キャリアドープされたマンガン酸化物系を解析する上で、系の乱れ(不純物効果)は避けて通れない問題である。本研究ではランダムポテンシャルを導入した二重交換模型を理論的に取り扱い、臨界現象やスピン励起スペクトルなどを調べた。ランダムポテンシャルを強くするにつれ強磁性交換相互作用の平均値は減少するが、それよりさらに急激に臨界温度は減少し、転移点直上でのスピンクラスター的振る舞い(グリフィス相の可能性)が示唆された。また、乱れた系のスピン励起スペクトルは転移温度の低いマンガン酸化物系の実験結果と良く一致している。 3)マンガン酸化物の電荷・軌道状態が磁場によって整列状態と無秩序状態をどのように入れ替わるのかを放射光X線によって調べた(東北大村上Gとの共同研究)。また、マンガンの形式平均価数が3.375の近傍で、4+の一次元鎖に入った余分な電子がさらに整列を起こすことをTEM観察によって明らかにした(物質・材料研究機構松井Gとの共同研究)。 4)層状Mn酸化物ペロブスカイトLa_<2-2x>Sr_<1+2x>Mn_2O_7の軌道状態を明らかにし、また、軌道状態を測定する実験手法を開発するために、同一のロッドから得た単結晶を用いて、スピン波分散とモデル計算の比較、偏極中性子回折(有馬らとの共同研究)、磁気コンブトンプロファイル法などの複数の実験手段を用いて相補的な研究を進め、x=0.3-0.5の範囲における軌道状態を定量的に明らかにし、それが磁性や伝導にどのような影響を与えているかを示した。また、ホール濃度がx=0.5を越える高ドープ領域において存在する複数の秩序構造に関して、ホール濃度・温度依存性を詳細に研究した。電荷秩序相と金属相という全く異なる相が共存し、金属相に寄生する電荷密度の長周期構造の存在を明らかにした。

Research Products
(36 results)

All Other

All Publications (36 results)

[Publications] J.Akimitsu: "Antiferromagnetism and Spin Gap State in the two-leg Ladder System"J.Phys.Chem.Sol.. 65. 135-140 (2001)
[Publications] J.Nagamatsu, N.Nakagawa, T.Muranaka, Y.Zenitani, J.Akimitsu: "Superconductivity at 39K in magnesium diboride"Nature. Vol.410, No.6824. 63-64 (2001)
[Publications] C.Sekar, T.Watanabe, A.Matsuda, H.Shibata, Y.Zenitani, J.Akimitsu: "Crystal Growth, Structure, and Transport Properties of the Five-Leg Spin Ladder Compound La_8Cu_7O_<19>"J.Sol.Sta.Chem.. 156. 422-427 (2001)
[Publications] 秋光純: "新しい金属系超伝導体の発見"日経サイエンス. 6月号. 36-42 (2001)
[Publications] 秋光純: "エキゾチックなホウ素化合物"日本物理学会誌(学界ニュース). Vol.56, No.4. 267-268 (2001)
[Publications] T.Muranaka, S.Margadonna, I.Maurin, K.Brigatti, D.Colognesi, K.Prassides, Y.Iwasa, M.Arai, M.Takata, J.Akimitsu: "Vibrational Spectroscopy of Superconducting MgB_2 by Neutron Inelastic Scattering"J.Phys.Soc.Jpn.. Vol.70, Np.6. 1480-1482 (2001)
[Publications] T.Muranaka, J.Akimitsu, M.Sera: "Thermal transport properties of MgB_2"Phys.Rev.B. Vol.64. 020505-1-020505-3 (2001)
[Publications] K.Prassides, Y.Iwasa, T.Ito, H.Chi, K.Uehara, E.Nishibori, M.Takata, M.Sakata, Y.Ohishi, O.Shimomura, T.Muranaka, J.Akimitsu: "Compressibility of the MgB_2 superconductor"Phys.Rev.B. Vol.64. 012509-1-012509-4 (2001)
[Publications] T.Takahashi, T.Sato, S.Souma, T.Muranaka, J.Akimitsu: "High-Resolution Photoemission Study of MgB_2"Phys.Rev.Lett.. Vol.86 No.21. 4915-4917 (2001)
[Publications] B.Gorshunov, C.A.Kuntscher, P.Haas, M.Dressel, F.P.Mena, A.B.Kuz'menko, D.van der Marel, T.Muranaka, J.Akimitsu: "Optical measurements of the superconducting gap in MgB_2"Eur.Phys.J.B. 21. 159-161 (2001)
[Publications] E.Nishibori, M.Takata, M.Sakata, H.Tanaka, T.Muranaka, J.Akimitsu: "Bonding Nature in MgB_2"J.Phys.Soc.Jpn.. Vol.70 No.8. 2252-2254 (2001)
[Publications] H.Ohta, S.Okubo, T.Sakurai, T.Goto, K.Kirita, K.Ueda, Y.Uwatoko, T.Saito, M.Azuma, M.Takano, J.Akimitsu: "High-frequency ESR measurements using pulsed magnetic fields in Kobe"Physica B. Vol.294-295. 624-629 (2001)
[Publications] S.Okubo, T.Yamada, H.Ohta, T.Yokoo, J.Akimitsu, H.Nojiri, M.Motokawa: "High-field AFMR measurements of Nd_2BaNiO_5 single crystal in the submillimeter wave region"Physica B. 294-295. 51-54 (2001)
[Publications] R.Kadono, W.Higemoto, A.Koda, K.Ohishi, T.Yokoo, J.Akimitsu, M.Hedo, Y.Inada, Y.Onuki, E.Yamamoto, Y.Haga: "Possible nodal vortex state in CeRu_2"Phys.Rev.B. Vol.63. 224520-1-224520-16 (2001)
[Publications] M.Sera, H.Ichikawa, T.Yokoo, J.Akimitsu, M.Nishi, K.Kakurai, S.Kunii: "Anomalous Temperature Dependence of the Magnetic Field Induced Antiferromagnetic Moment in the Antiferroquadrupolar Orderd State of CeB_6"Phys.Rev.Lett.. Vol.86, No.8. 1578-1581 (2001)
[Publications] 秋光純: "RuSr_2RECu_2O_8(RE=Sm, Eu, Gd, Y)における超伝導と磁性の共存"固体物理. Vol.36, No.7. 413-418 (2001)
[Publications] J.Akimitsu, K.Takenawa, K.Suzuki, H.Harima, Y.Kuramoto: "High-Temperature Ferromagnetism in CaB_2C_2"Science. Vol.293. 1125-1127 (2001)
[Publications] Yukitoshi Motome, Nobuo Furukawa: "Critical Phenomena of Ferromagnetic Transition in Double-Exchange Systems"Journal of the Physical Society of Japan. 70・6. 1487 (2001)
[Publications] Nobuo Furukawa: "Antiferromagnetism of the Hubbard Model on a Layered Honeycomb Lattice-Is MgB_2 a Nearly-Antiferromagnetic Metal?-"Journal of the Physical Society of Japan. 70・6. 1483 (2001)
[Publications] Yukitoshi Motome, Nobuo Furukawa: "Non-equilibrium Relaxation Study of Ferromagnetic Transition in Double-Exchange Systems"Journal of the Physical Society of Japan. 70・9. 2802 (2001)
[Publications] Nobuo Furukawa, Yukitoshi Motome, Hisaho Nakata: "Monte Carlo Algorithm for the Double Exchange Model Optimized for Parallel Computations"Computer Physics Communications. 142-1. 410 (2001)
[Publications] Nobuo Furukawa, Y.Shimomura, T.Akimoto, Y.Moritomo: "Magnon scattering processes and low temperature resistivity in CMR manganites"Journal of Magnetism and Magnetic Materials. 226-230. 782 (2001)
[Publications] Yukitoshi Motome, Nobuo Furukawa: "Anomaly in Spin Excitation Spectrum of Double-Exchange Systems with Randomness"Journal of the Physical Society of Japan. 71・5(to be published, 未定). (2002)
[Publications] Yukitoshi Motome, Nobuo Furukawa: "Impurity Effect on Ferromagnetic Transition in Double-Exchange Systems"Journal of Physics and Chemistry of Solids. (to be published, 未定). (2002)
[Publications] Yukitoshi Motome, Nobuo Furukawa: "Critical Exponents for the Ferromagnetism in Colossal Magnetoresistance Manganites"Applied Physics A.. (to be published, 未定). (2002)
[Publications] T.Asaka, S.Yamada, S.Tsutsumi, C.Tsuruta, K.Kimoto, T.Arima, Y.Matsui: "Charge/Orbital Ordering Structure of Pr_<1-x>Ca_xMnO_3(x=3/8) Examined by Low-Temperature Transmission Electron Microscopy"Phys.Rev.Lett.. 88・9. 097201 (2002)
[Publications] T.Asaka, S.Tsutsumi, S.Yamada, T.Arima, C.Tsuruta, K.Kimoto, Y.Matsui: "Charge/Orbital ordering structure and microstructure of Pr1-xCa_xMnO_3($x<0.5$) studied by low-temperature TEM"Physica C. 357-360. 313-317 (2001)
[Publications] E.Saito, T.Taknenobu, T.Ito, Y.Iwasa, K.Prassides, T.Arima: "Pressure dependence of T-c in the MgB_2 superconductor as probed by resistivity measurements"J.Phys.-Cond.Matt.. 13. L267-L270 (2001)
[Publications] M.v.Zimmermann, C.S.Nelson, Y.-J.Kim, J.P.Hill, D.Gibbs, H.Nakao, Y.Wakabayashi, Y.Murakami, Y.Tokura, Y.Tomioka, T.Arima, C.-C.Kao, D.Casa, C.Venkataraman, Th.Gog: "Resonant x-ray-scattering study of octahedral tilt ordering in LaMnO_3 and Pr_<1-x>Ca_xMnO_3"Phys.Rev.B. 64・6. 064411 (2001)
[Publications] M.Kubota, K.Hirota, Y.Endoh, et al.: "Examination of spin fluctuations within the MnO_2 layers in a bilayer manganite La_<1.1>Sr_<1.9>Mn_2O_7"J.Phys.Chem.Solids. Vol.62. 317-319 (2001)
[Publications] K.Tsuda, M.Tanaka, K.Hirota, Y.Endoh: "Convergent-Beam Electron Diffraction Study of the Low-Temperature Ferromagnetic Insulator Phase of La_<1-x>Sr_xMnO_3(x=0.11, 0.12)"J.Phys.Soc.Japan. Vol.70. 1010-1014 (2001)
[Publications] D.E.Cox, K.Hirota, Y.Endoh, et al.: "Vertical boundary at x ￣0.11 in the structural phase diagram of the La_<1-x>Sr_xMnO_3 system (0.08<=x<=0.125)"Physical Review B. Vol.64, 2. 24431:1-9 (2001)
[Publications] A.Koizumi, K.Hirota, et al.: "Study of the e_g Orbitals in the Bilayer Manganite La_<2-2x>Sr_<1+2x>Mn_2O_7 by using Magnetic Compton-Profile Measurement"Physical Review Letters. Vol.86. 5589-5592 (2001)
[Publications] T.Matsumura, K.Hirota, Y.Endoh, et al.: "Observation of the antiferroquadrupolar order in DyB_2C_2 by resonant x-ray scattering"Physical Review B. Vol.62, 9. 094420:1-11 (2002)
[Publications] K.Hirota, Y.Endoh, et al.: "Spin dynamical properties and orbital states of the layered perovskite La_<2-2x>Sr_<1+2x>Mn_2O_7(0.3<=x<0.5)"Physical Review B. Vol.65, 6. 064414:1-10 (2002)
[Publications] 藤井保彦編 (廣田和馬, 村上洋一他): "実験物理学講座5:構造解析 (第5章トピックス放射光-中性子-電子線による軌道秩序の観測 [pp.325-362])"丸善. 392 (2001)

2001 Fiscal Year Annual Research Report

軌道相転移の制御による新物質創製

Principal Investigator

秋光 純 青山学院大学, 理工学部, 教授 (80013522)

Research Products

[Publications] J.Akimitsu: "Antiferromagnetism and Spin Gap State in the two-leg Ladder System"J.Phys.Chem.Sol.. 65. 135-140 (2001)

[Publications] J.Nagamatsu, N.Nakagawa, T.Muranaka, Y.Zenitani, J.Akimitsu: "Superconductivity at 39K in magnesium diboride"Nature. Vol.410, No.6824. 63-64 (2001)

[Publications] C.Sekar, T.Watanabe, A.Matsuda, H.Shibata, Y.Zenitani, J.Akimitsu: "Crystal Growth, Structure, and Transport Properties of the Five-Leg Spin Ladder Compound La_8Cu_7O_<19>"J.Sol.Sta.Chem.. 156. 422-427 (2001)

[Publications] 秋光 純: "新しい金属系超伝導体の発見"日経サイエンス. 6月号. 36-42 (2001)

[Publications] 秋光 純: "エキゾチックなホウ素化合物"日本物理学会誌(学界ニュース). Vol.56, No.4. 267-268 (2001)

[Publications] T.Muranaka, S.Margadonna, I.Maurin, K.Brigatti, D.Colognesi, K.Prassides, Y.Iwasa, M.Arai, M.Takata, J.Akimitsu: "Vibrational Spectroscopy of Superconducting MgB_2 by Neutron Inelastic Scattering"J.Phys.Soc.Jpn.. Vol.70, Np.6. 1480-1482 (2001)

[Publications] T.Muranaka, J.Akimitsu, M.Sera: "Thermal transport properties of MgB_2"Phys.Rev.B. Vol.64. 020505-1-020505-3 (2001)

[Publications] K.Prassides, Y.Iwasa, T.Ito, H.Chi, K.Uehara, E.Nishibori, M.Takata, M.Sakata, Y.Ohishi, O.Shimomura, T.Muranaka, J.Akimitsu: "Compressibility of the MgB_2 superconductor"Phys.Rev.B. Vol.64. 012509-1-012509-4 (2001)

[Publications] T.Takahashi, T.Sato, S.Souma, T.Muranaka, J.Akimitsu: "High-Resolution Photoemission Study of MgB_2"Phys.Rev.Lett.. Vol.86 No.21. 4915-4917 (2001)

[Publications] B.Gorshunov, C.A.Kuntscher, P.Haas, M.Dressel, F.P.Mena, A.B.Kuz'menko, D.van der Marel, T.Muranaka, J.Akimitsu: "Optical measurements of the superconducting gap in MgB_2"Eur.Phys.J.B. 21. 159-161 (2001)

[Publications] E.Nishibori, M.Takata, M.Sakata, H.Tanaka, T.Muranaka, J.Akimitsu: "Bonding Nature in MgB_2"J.Phys.Soc.Jpn.. Vol.70 No.8. 2252-2254 (2001)

[Publications] H.Ohta, S.Okubo, T.Sakurai, T.Goto, K.Kirita, K.Ueda, Y.Uwatoko, T.Saito, M.Azuma, M.Takano, J.Akimitsu: "High-frequency ESR measurements using pulsed magnetic fields in Kobe"Physica B. Vol.294-295. 624-629 (2001)

[Publications] S.Okubo, T.Yamada, H.Ohta, T.Yokoo, J.Akimitsu, H.Nojiri, M.Motokawa: "High-field AFMR measurements of Nd_2BaNiO_5 single crystal in the submillimeter wave region"Physica B. 294-295. 51-54 (2001)

[Publications] R.Kadono, W.Higemoto, A.Koda, K.Ohishi, T.Yokoo, J.Akimitsu, M.Hedo, Y.Inada, Y.Onuki, E.Yamamoto, Y.Haga: "Possible nodal vortex state in CeRu_2"Phys.Rev.B. Vol.63. 224520-1-224520-16 (2001)

[Publications] M.Sera, H.Ichikawa, T.Yokoo, J.Akimitsu, M.Nishi, K.Kakurai, S.Kunii: "Anomalous Temperature Dependence of the Magnetic Field Induced Antiferromagnetic Moment in the Antiferroquadrupolar Orderd State of CeB_6"Phys.Rev.Lett.. Vol.86, No.8. 1578-1581 (2001)

[Publications] 秋光 純: "RuSr_2RECu_2O_8(RE=Sm, Eu, Gd, Y)における超伝導と磁性の共存"固体物理. Vol.36, No.7. 413-418 (2001)

[Publications] J.Akimitsu, K.Takenawa, K.Suzuki, H.Harima, Y.Kuramoto: "High-Temperature Ferromagnetism in CaB_2C_2"Science. Vol.293. 1125-1127 (2001)

[Publications] Yukitoshi Motome, Nobuo Furukawa: "Critical Phenomena of Ferromagnetic Transition in Double-Exchange Systems"Journal of the Physical Society of Japan. 70・6. 1487 (2001)

[Publications] Nobuo Furukawa: "Antiferromagnetism of the Hubbard Model on a Layered Honeycomb Lattice-Is MgB_2 a Nearly-Antiferromagnetic Metal?-"Journal of the Physical Society of Japan. 70・6. 1483 (2001)

[Publications] Yukitoshi Motome, Nobuo Furukawa: "Non-equilibrium Relaxation Study of Ferromagnetic Transition in Double-Exchange Systems"Journal of the Physical Society of Japan. 70・9. 2802 (2001)

[Publications] Nobuo Furukawa, Yukitoshi Motome, Hisaho Nakata: "Monte Carlo Algorithm for the Double Exchange Model Optimized for Parallel Computations"Computer Physics Communications. 142-1. 410 (2001)

[Publications] Nobuo Furukawa, Y.Shimomura, T.Akimoto, Y.Moritomo: "Magnon scattering processes and low temperature resistivity in CMR manganites"Journal of Magnetism and Magnetic Materials. 226-230. 782 (2001)

[Publications] Yukitoshi Motome, Nobuo Furukawa: "Anomaly in Spin Excitation Spectrum of Double-Exchange Systems with Randomness"Journal of the Physical Society of Japan. 71・5(to be published, 未定). (2002)

[Publications] Yukitoshi Motome, Nobuo Furukawa: "Impurity Effect on Ferromagnetic Transition in Double-Exchange Systems"Journal of Physics and Chemistry of Solids. (to be published, 未定). (2002)

[Publications] Yukitoshi Motome, Nobuo Furukawa: "Critical Exponents for the Ferromagnetism in Colossal Magnetoresistance Manganites"Applied Physics A.. (to be published, 未定). (2002)

[Publications] T.Asaka, S.Yamada, S.Tsutsumi, C.Tsuruta, K.Kimoto, T.Arima, Y.Matsui: "Charge/Orbital Ordering Structure of Pr_<1-x>Ca_xMnO_3(x=3/8) Examined by Low-Temperature Transmission Electron Microscopy"Phys.Rev.Lett.. 88・9. 097201 (2002)

[Publications] T.Asaka, S.Tsutsumi, S.Yamada, T.Arima, C.Tsuruta, K.Kimoto, Y.Matsui: "Charge/Orbital ordering structure and microstructure of Pr1-xCa_xMnO_3($x<0.5$) studied by low-temperature TEM"Physica C. 357-360. 313-317 (2001)

[Publications] E.Saito, T.Taknenobu, T.Ito, Y.Iwasa, K.Prassides, T.Arima: "Pressure dependence of T-c in the MgB_2 superconductor as probed by resistivity measurements"J.Phys.-Cond.Matt.. 13. L267-L270 (2001)

[Publications] M.Kubota, K.Hirota, Y.Endoh, et al.: "Examination of spin fluctuations within the MnO_2 layers in a bilayer manganite La_<1.1>Sr_<1.9>Mn_2O_7"J.Phys.Chem.Solids. Vol.62. 317-319 (2001)

[Publications] K.Tsuda, M.Tanaka, K.Hirota, Y.Endoh: "Convergent-Beam Electron Diffraction Study of the Low-Temperature Ferromagnetic Insulator Phase of La_<1-x>Sr_xMnO_3(x=0.11, 0.12)"J.Phys.Soc.Japan. Vol.70. 1010-1014 (2001)

[Publications] D.E.Cox, K.Hirota, Y.Endoh, et al.: "Vertical boundary at x ￣0.11 in the structural phase diagram of the La_<1-x>Sr_xMnO_3 system (0.08<=x<=0.125)"Physical Review B. Vol.64, 2. 24431:1-9 (2001)

[Publications] A.Koizumi, K.Hirota, et al.: "Study of the e_g Orbitals in the Bilayer Manganite La_<2-2x>Sr_<1+2x>Mn_2O_7 by using Magnetic Compton-Profile Measurement"Physical Review Letters. Vol.86. 5589-5592 (2001)

[Publications] T.Matsumura, K.Hirota, Y.Endoh, et al.: "Observation of the antiferroquadrupolar order in DyB_2C_2 by resonant x-ray scattering"Physical Review B. Vol.62, 9. 094420:1-11 (2002)

[Publications] K.Hirota, Y.Endoh, et al.: "Spin dynamical properties and orbital states of the layered perovskite La_<2-2x>Sr_<1+2x>Mn_2O_7(0.3<=x<0.5)"Physical Review B. Vol.65, 6. 064414:1-10 (2002)

[Publications] 藤井保彦編 (廣田和馬, 村上洋一他): "実験物理学講座5:構造解析 (第5章 トピックス 放射光-中性子-電子線による軌道秩序の観測 [pp.325-362])"丸善. 392 (2001)

秋光純青山学院大学, 理工学部, 教授 (80013522)

[Publications] 秋光純: "新しい金属系超伝導体の発見"日経サイエンス. 6月号. 36-42 (2001)

[Publications] 秋光純: "エキゾチックなホウ素化合物"日本物理学会誌(学界ニュース). Vol.56, No.4. 267-268 (2001)

[Publications] 秋光純: "RuSr_2RECu_2O_8(RE=Sm, Eu, Gd, Y)における超伝導と磁性の共存"固体物理. Vol.36, No.7. 413-418 (2001)

[Publications] 藤井保彦編 (廣田和馬, 村上洋一他): "実験物理学講座5:構造解析 (第5章トピックス放射光-中性子-電子線による軌道秩序の観測 [pp.325-362])"丸善. 392 (2001)