1994 Fiscal Year Annual Research Report

高温超伝導の科学:総括班

Research Project

Project/Area Number	04240101
Research Institution	Tohoku University
Principal Investigator	立木昌東北大学, 金属材料研究所, 教授 (20028111)
Co-Investigator(Kenkyū-buntansha)	井口家成東京工業大学, 理学部, 教授 (10011173) 北沢宏一東京大学, 工学部, 教授 (90011189) 佐藤正俊名古屋大学, 理学部, 教授 (40092225) 坂東尚周京都大学, 化学研究所, 教授 (70027027) 福山秀敏東京大学, 大学院理学系研究科, 教授 (10004441)
Keywords	高温超伝導 / ミニ研究会 / ニュースレター / 異常金属相 / スピンギャップ / d波超伝導 / 超伝導デバイス / 高圧合成法
Research Abstract	本総括班は、重点領域研究「高温超伝導の科学」の活発な研究活動を促すとともに、プロジェクト研究としての目標達成のために次のような活動を行なった。重要テーマに焦点を絞った6回のミニ研究会を開き、1月には本領域研究全体の研究成果発表会を公開で開催し計90件の報告があった。また、情報交換を目的としたニュースレターを年4回発行した。本年度は本重点領域研究の最終年度であるため、領域全体として実のりある研究成果を挙げるべく、とりまとめに重点をおいた。主な成果は次のとおりである。1.現在最高のTcをもつ水銀系超伝導体にレニウムを添加すると、高Tc相が安定化し、同時に不可逆磁場を上昇することが分かった。この結果、高温超伝導体を77Kで実用化する可能性が見えてきた。2.銅酸化物の常伝導相が新型の反強磁性モット絶縁体近傍に位置する異常金属相であり、その形成とスピンギャップの存在の関連が、種々の実験により明らかにされた。3.その異常金属相の低エネルギー励起を特徴づける電子状態の理論的研究が、スピン・電荷分離の立場、フェルミ流体の立場から行なわれ、実験結果と比較検討することによりその性質が明らかになった。4.NMR、光電子分光、トンネル効果等の実験結果から高温超伝導体の電子対の対称性はd波である可能性が強くなった。5.超伝導層に垂直な方向に偏ったプラズマ振動モードは超伝導ギャップの中に現われる。これを励起することによりサブミリ波発光素子等、高温超伝導体独特のデバイスの可能性が指摘された。6.高圧合成法によりスピン梯子格子をもつSr_<n-1>Cu_<n+1>O_<2n>を合成し、梯子の足が偶数相ではスピンギャップが存在し、奇数相では存在しないという理論的予測を実験的に確認した。

Research Products
(27 results)

All Other

All Publications (27 results)

[Publications] T.Koyama: "Study of supreconducting fluctuations in superconductors with strong fluctuations" Physica C. 221. 91-103 (1994)
[Publications] M.Tachiki: "Electromagnetic phenomena related to a low-frequency plasma in cuprate superconductors" Phys.Rev.B. 50. 7065-7084 (1994)
[Publications] L.N.Buelavskii: "Low Frequency Magento-optical Properties of Josephson-Coupled Superconductors" Phys.Rev.B. 74. 801-804 (1994)
[Publications] T.Tanamoto: "Magnetic Properties of Extended t-J Modell II.Dynamical Properties" J.Phys.Soc.Jpn.63. 2739-2759 (1994)
[Publications] M.Hayashi: "Dynamical Superflued Density in Vortex State of Type II Superconductors" J.Phys.Soc.Jpn.63. 3369-3391 (1994)
[Publications] H.Fukuyama: "Spin excitations in High Tc Cuprates" J.Low Temp.Phys.95. 309-321 (1994)
[Publications] Y.Bando: "Growth Mechanism of YBa_2Cu_3O_<7-X> by Reactive Coevaporation and Superconductivity of the One-Unit-Cell Layer" Trans.Mat.Soc.Jpn.(ed.H.Sasaki,et al.). 19A. 499-504 (1994)
[Publications] Y.Yano: "Epitaxial Growth and Dielectric Properties of BaTiO_3 Films on Pt Electrodes by Reactive Evalporation" J.Appl.Phys.76. 7833-7838 (1994)
[Publications] T.Kawahara: "Electric Field Effects on Transport Properties in YBa_2Cu_3O_<7->δ" Physica C. 235-240. 3363-3364 (1994)
[Publications] T.Nishikawa: "Transport Anomalies of Misfit Layer Compounds La_<1.17-X>Sr_XVS_<3.17> with Mott Metal-Insulator Transition" J.Phys.Soc.Jpn.63. 3218-3221 (1994)
[Publications] J.Takeda: "Transport and Magnetic Studes of BaCo_<1-X>Ni_2S_2" J.Phys.Soc.Jpn.63. 3564-3567 (1994)
[Publications] H.Harashina: "Superconductivity-Induced Anomalies in c-Axis Polarized Phonon Modes of YBa_2Cu_3O_7 Studied by Neutron Inelastic scattering" J.PHys.Soc.Jpn.(in press).
[Publications] T.Hasegawa: "Tunneling Spectroscopic Measurements on Boride Carbide Superconductors" Physica C. 235-240. 1859-1860 (1994)
[Publications] M.Nantoh: "Cryogenic Scanning Tunneling Microscopy/Spectroscopy on the (110)Surface of YBa_2Cu_3O_y Epitaxials Thin Films" Physica C. (in press).
[Publications] T.Hasegawa: "STM Tunneling Spectroscopy on Hihg Tc Superconductors" J.Superconductivity. (in press).
[Publications] K.Lee: "Direct observation of Josephson self-radiation in Bi_2Sr_2Ca_2Cu_3O_y break junctions above 77K" Appl.Phys.Lett.64. 1729-1731 (1994)
[Publications] I.Iguchi: "Dynamic Cooper-pair breaking by tunneling injection of quasiparticles into a high-Tc YBa_2Cu_3O_7 superconductor" Phys.Rev.B. 50. 457-461 (1994)
[Publications] I.Iguchi: "Exper lmental evidence for a d-wave pairing state in YBa_2Cu_3O_<7-y> from a study of YBa_2Cu_3O_<7-y>/Insulator/Pb Josephson tunnel junctions" Phys.rev.B. 49. 12388-12391 (1994)
[Publications] Y.Tokura: "Metal-Insulator Phenomena in 3d Transition Metal Oxides" Physica C. 235-240. 138-141 (1994)
[Publications] Y.Tokura: "Giant Magnetotransport Phenomena in Filling-Controled Kondo Lattice System:La_<1-x>Sr_xMnO_3" J.Phys.Soc.Jpn.63. 3931-3935 (1994)
[Publications] T.Katsufuji: "Anomalous variation of phonon Raman intensities near the metal-to-Mott-insulator transition in titanium oxide systems" Phys.Rev.B. 49. 4372-4375 (1994)
[Publications] H.Nameki: "Effects of lanthanoid substitution on superocnductivity and modulated structure of Bi_2Sr_2CuO_y" Phusica C. 234. 255-262 (1994)
[Publications] E.Ohshima: "Structure analysis of oxygen-deficient TISr_2CuO_y by neutron diffraction and high-resolution electron microscopy" Physica C. 221. 261-268 (1994)
[Publications] S.Nakajima: "Effectiveness of high-pressure synthesis of bulk high-temperature superconductors of Hg-Ba-Ca-Cu-O system" Jpn.J.Appl.Phys.33. 1863-1864 (1994)
[Publications] K.Yoshida: "Ion-Size Effects on the Structure and Superconductivity of La-214 Compounds at 1/8 Doping" Physica C. 230. 371-377 (1994)
[Publications] M.Nohara: "Unconventional Enhancement of Elastic Constants in Superconducting La_<2-x>Sr_DCuO_4" Physica C. 235-240. 1249-1250 (1994)
[Publications] Y.Maeno: "Superconductivity in a Layered Perovskite without Copper" Nature. 372. 532-534 (1994)

1994 Fiscal Year Annual Research Report

高温超伝導の科学:総括班

Principal Investigator

立木 昌 東北大学, 金属材料研究所, 教授 (20028111)

Research Products

[Publications] T.Koyama: "Study of supreconducting fluctuations in superconductors with strong fluctuations" Physica C. 221. 91-103 (1994)

[Publications] M.Tachiki: "Electromagnetic phenomena related to a low-frequency plasma in cuprate superconductors" Phys.Rev.B. 50. 7065-7084 (1994)

[Publications] L.N.Buelavskii: "Low Frequency Magento-optical Properties of Josephson-Coupled Superconductors" Phys.Rev.B. 74. 801-804 (1994)

[Publications] T.Tanamoto: "Magnetic Properties of Extended t-J Modell II.Dynamical Properties" J.Phys.Soc.Jpn.63. 2739-2759 (1994)

[Publications] M.Hayashi: "Dynamical Superflued Density in Vortex State of Type II Superconductors" J.Phys.Soc.Jpn.63. 3369-3391 (1994)

[Publications] H.Fukuyama: "Spin excitations in High Tc Cuprates" J.Low Temp.Phys.95. 309-321 (1994)

[Publications] Y.Bando: "Growth Mechanism of YBa_2Cu_3O_<7-X> by Reactive Coevaporation and Superconductivity of the One-Unit-Cell Layer" Trans.Mat.Soc.Jpn.(ed.H.Sasaki,et al.). 19A. 499-504 (1994)

[Publications] Y.Yano: "Epitaxial Growth and Dielectric Properties of BaTiO_3 Films on Pt Electrodes by Reactive Evalporation" J.Appl.Phys.76. 7833-7838 (1994)

[Publications] T.Kawahara: "Electric Field Effects on Transport Properties in YBa_2Cu_3O_<7->δ" Physica C. 235-240. 3363-3364 (1994)

[Publications] T.Nishikawa: "Transport Anomalies of Misfit Layer Compounds La_<1.17-X>Sr_XVS_<3.17> with Mott Metal-Insulator Transition" J.Phys.Soc.Jpn.63. 3218-3221 (1994)

[Publications] J.Takeda: "Transport and Magnetic Studes of BaCo_<1-X>Ni_2S_2" J.Phys.Soc.Jpn.63. 3564-3567 (1994)

[Publications] H.Harashina: "Superconductivity-Induced Anomalies in c-Axis Polarized Phonon Modes of YBa_2Cu_3O_7 Studied by Neutron Inelastic scattering" J.PHys.Soc.Jpn.(in press).

[Publications] T.Hasegawa: "Tunneling Spectroscopic Measurements on Boride Carbide Superconductors" Physica C. 235-240. 1859-1860 (1994)

[Publications] M.Nantoh: "Cryogenic Scanning Tunneling Microscopy/Spectroscopy on the (110)Surface of YBa_2Cu_3O_y Epitaxials Thin Films" Physica C. (in press).

[Publications] T.Hasegawa: "STM Tunneling Spectroscopy on Hihg Tc Superconductors" J.Superconductivity. (in press).

[Publications] K.Lee: "Direct observation of Josephson self-radiation in Bi_2Sr_2Ca_2Cu_3O_y break junctions above 77K" Appl.Phys.Lett.64. 1729-1731 (1994)

[Publications] I.Iguchi: "Dynamic Cooper-pair breaking by tunneling injection of quasiparticles into a high-Tc YBa_2Cu_3O_7 superconductor" Phys.Rev.B. 50. 457-461 (1994)

[Publications] I.Iguchi: "Exper lmental evidence for a d-wave pairing state in YBa_2Cu_3O_<7-y> from a study of YBa_2Cu_3O_<7-y>/Insulator/Pb Josephson tunnel junctions" Phys.rev.B. 49. 12388-12391 (1994)

[Publications] Y.Tokura: "Metal-Insulator Phenomena in 3d Transition Metal Oxides" Physica C. 235-240. 138-141 (1994)

[Publications] Y.Tokura: "Giant Magnetotransport Phenomena in Filling-Controled Kondo Lattice System:La_<1-x>Sr_xMnO_3" J.Phys.Soc.Jpn.63. 3931-3935 (1994)

[Publications] T.Katsufuji: "Anomalous variation of phonon Raman intensities near the metal-to-Mott-insulator transition in titanium oxide systems" Phys.Rev.B. 49. 4372-4375 (1994)

[Publications] H.Nameki: "Effects of lanthanoid substitution on superocnductivity and modulated structure of Bi_2Sr_2CuO_y" Phusica C. 234. 255-262 (1994)

[Publications] E.Ohshima: "Structure analysis of oxygen-deficient TISr_2CuO_y by neutron diffraction and high-resolution electron microscopy" Physica C. 221. 261-268 (1994)

[Publications] S.Nakajima: "Effectiveness of high-pressure synthesis of bulk high-temperature superconductors of Hg-Ba-Ca-Cu-O system" Jpn.J.Appl.Phys.33. 1863-1864 (1994)

[Publications] K.Yoshida: "Ion-Size Effects on the Structure and Superconductivity of La-214 Compounds at 1/8 Doping" Physica C. 230. 371-377 (1994)

[Publications] M.Nohara: "Unconventional Enhancement of Elastic Constants in Superconducting La_<2-x>Sr_DCuO_4" Physica C. 235-240. 1249-1250 (1994)

[Publications] Y.Maeno: "Superconductivity in a Layered Perovskite without Copper" Nature. 372. 532-534 (1994)

立木昌東北大学, 金属材料研究所, 教授 (20028111)