1993 Fiscal Year Annual Research Report

高温超伝導の科学・第4班(超伝導特性班)

Research Project

Project/Area Number	04240104
Research Institution	The University of Tokyo
Principal Investigator	北沢宏一東京大学, 工学部, 教授 (90011189)
Co-Investigator(Kenkyū-buntansha)	青峰隆文九州大学, 理学部, 教授 (50037206) 松下照男九州工業大学, 情報工学部, 教授 (90038084) 長村光造京都大学, 工学部, 教授 (50026209) 氷上忍東京大学, 教養学部, 教授 (30093298) 小林典男東北大学, 金属材料研究所, 教授 (40111306)
Keywords	超伝導 / 臨界電流 / ピン止め / ボルテックス / 超伝導ゆらぎ / コヒーレンス長 / 臨界磁場
Research Abstract	本分野は超伝導研究の中で唯一、我国が他国に全体として水を空けられている分野である。しかしながらいくつかのユニークな研究が展開されており、本班の組織化によって全体としての研究レベルの向上と、ユニークな研究の進展をはかるのが目的であった。その意味で本班のまず最大の業績は組織化された努力によって、超伝導現象論の学問分野が我国の研究者の中に根付きはじめたことである。第2の点として、我国の研究から提唱され始めた超伝導ゆらぎの現象が根本的には全世界に受け容れられ、それが理論的にも実験的にも深められつつある状況となった。このような観点から、磁界と電流、結晶構造の相対角度を精密制御する測定によりユニークで、かつ、良質単結晶を用いて、より定量的な研究がなされた。またこのゆらぎ領域を記述する理論の展開が行われ、いくつかの物理量を予言するに至っている。一方、このようなゆらぎ領域と抵抗がゼロとなる領域との境界は不可逆線と呼ばれるようになり、高温超伝導体の異方性との関連を注目する研究がいくつか行われるようになった。一方、抵抗がゼロとなる不可逆領域内でも、熱活性化によるクリープ現象が観測される。これは実用上も大変に重要な現象であり、多くの研究例があるが、本研究ではそのための新しいアプローチがいくつかなされるようになった。その例は、ホール素子を使用しての実験やあるいは磁歪を利用してのユニークなものである。コヒーレンス及び磁気侵入に関する研究にSTMやマイクロ波測定が適用され、独自の方法として結果が出されている。これらはまだいずれも充分深まったとはいえないが新しいアプローチとして今後の発展を期待してよいと考えられる。

Research Products

(24 results)

All Other

All Publications (24 results)

[Publications] H.Ikuta: "Giant Magnetostriction in Bi_2Sr_2CaCu_2O_8 Single Crystal in the Superconducti g State and Its Mechanism" Phy.Rev.Lett.70. 2166-2169 (1993)
[Publications] Y.Tomioka: "The Meissner and shielding effects in niobium in relation to oxide superconductors" Physica C. 215. 297-304 (1993)
[Publications] T.Hasegawa: "Scanning Tunneling Spectroscopy on High T_c Superconductors" J.Phys.Chem.Solids. 54. 1351-1357 (1993)
[Publications] H.Iwasaki: "Anomalous magnetoresistance in the normal state of Y_<1-x>Pr_xBa_2Cu_3O_y(x>0.6)films" Physica C. 204. 406-412 (1993)
[Publications] S.Awaji: "Dimensional crossover effect of pinning in YBa_2Cu_3O_7 films" Jpn.J.Appl.Phys.32. L1795-L1797 (1993)
[Publications] K.Watanabe: "Irreversibility line and flux pinning in High T_c YBa_2Cu_3O_7 Superconductivity" Advances in Superconductivity. 5. 459-462 (1993)
[Publications] K.Watanabe: "Anisotropy and dimensional characteristics in CVD route YBa_2Cu_3O_<7-y>" Materials Science Forrum. 137-139. 277-288 (1993)
[Publications] N.Kobayashi: "Fluctuation effects in specific heat and magnetization of C-axis alligned(Bi,Pb)_2Sr_2Ca_2Cu_3O_x" Physica C. 219. 265-272 (1993)
[Publications] K.Matsuzaki: "Layered structure and superconducting properties of Ag-sheathed Bi_<1.84>Pb_<0.34>Sr_2Ca_2Cu_3O_y wires prepared by a combined jellyroll and hot extrusion technique" Jpn.J.Appl.Phys.64. (1994)
[Publications] Yoshitake: "Numerical Study on the Conductance of Normal-Superconductor Contacts" J.Phys.Soc.Jpn.62. 1844-1847 (1993)
[Publications] K.Tanaka: "Three-dimensional t-J model and cluster variation method" Physica B. (印刷中).
[Publications] K.Kishio: "Crystal Structure and Anisotropy of Iodine-Intercalated Bi_2Sr_2Ca_<n-1>Cu_nO_y" J.Superconductivity. 7. 117-121 (1994)
[Publications] M.Okuya: "Single Crystal Growth and Anisotropic Electrical Properties of(La_<1-x>Ca_x)_2CaCu_2O_6" J.Superconductivity. 7. 313-318 (1994)
[Publications] J.Shimoyama: "New Mercury-based Superconductor;(Hg,Cr)Sr_2CuO_y" Physica C. (印刷中).
[Publications] A.G.Aronov: "Gauge invariance and transport properties in superconductors above T_c" Phys.Rev.B. (in press). (1994)
[Publications] S.Ochiai: "Improvement of strain dependence of critical current of Ag/Bi2223 tapes by reducing oxide core fraction" Cryogenics. 33. 976-979 (1993)
[Publications] K.Osamura: "Phase diagram of Ln-Ba-Cu-O system(Ln=Lanthanide)" Z.Metallkde. 84. 532-538 (1993)
[Publications] K.Osamura: "Influence of Ag addition on J_c and mechanical properties of Ag/Bi2223 tapes" Advances in Superconductivity. 5. 689-692 (1993)
[Publications] S.Ochiai: "Estimation of strength distribution of Nb_3Sn in multifilamentary composite wire" J.Appl.Phys.74. 440-445 (1993)
[Publications] R.Ikeda: "Implications of Fluctuation Effects on Thermodynamic Quantities in Type II Superconductors" Physica B.
[Publications] X.G.Qiu: "Thermally activated flux dissipation in c-axis-oriented YBa_2Cu_3O_7/PrBa_2Cu_3O_7 multilayers" Phys.Rev.B. 47. 14519-14524 (1993)
[Publications] C.PanagopoulosT.FukamiT.Matsushita: "The effects of gaseous helium and nitrogen to the thermopower measurements:A note of concern for the discrepancy of the results observed in high temperature superconductorsMagnetic field-direction dependence of critical current density in c-axis oriented Bi_2Sr_<1.7>La_<0.3>CuO_<6+y> filmsEffect of Coherence Length in the C-axis on Irreversibility Properties in Anisotropic High Temperature Superconductors" Jpn.J.Appl.Phys.Physica CAdvances in Superconductivity. 32215V. 4684-4689375-381455-458 (199319931993)
[Publications] K.Matsuzaki: "High Temperature Superconducting Electronics(Microstructure and superconducting properties on hot extruded Tl- and Bi-based oxide)" OHMsha, 11 (1993)
[Publications] K.Watanabe: "Advances in High-T_c Superconductors(editted by J.J.Pouch,S.A.Alterovitz and R.R.Romanofsky)(Anisotropy and Dimensional Characteristic in CVD Route Y_1Ba_2Cu_3O_<7-d>)" Trans Tech Publications,Aedermannsdorf,Switzerland, 797 (1993)

1993 Fiscal Year Annual Research Report

高温超伝導の科学・第4班(超伝導特性班)

Principal Investigator

北沢 宏一 東京大学, 工学部, 教授 (90011189)

Research Products

[Publications] H.Ikuta: "Giant Magnetostriction in Bi_2Sr_2CaCu_2O_8 Single Crystal in the Superconducti g State and Its Mechanism" Phy.Rev.Lett.70. 2166-2169 (1993)

[Publications] Y.Tomioka: "The Meissner and shielding effects in niobium in relation to oxide superconductors" Physica C. 215. 297-304 (1993)

[Publications] T.Hasegawa: "Scanning Tunneling Spectroscopy on High T_c Superconductors" J.Phys.Chem.Solids. 54. 1351-1357 (1993)

[Publications] H.Iwasaki: "Anomalous magnetoresistance in the normal state of Y_<1-x>Pr_xBa_2Cu_3O_y(x>0.6)films" Physica C. 204. 406-412 (1993)

[Publications] S.Awaji: "Dimensional crossover effect of pinning in YBa_2Cu_3O_7 films" Jpn.J.Appl.Phys.32. L1795-L1797 (1993)

[Publications] K.Watanabe: "Irreversibility line and flux pinning in High T_c YBa_2Cu_3O_7 Superconductivity" Advances in Superconductivity. 5. 459-462 (1993)

[Publications] K.Watanabe: "Anisotropy and dimensional characteristics in CVD route YBa_2Cu_3O_<7-y>" Materials Science Forrum. 137-139. 277-288 (1993)

[Publications] N.Kobayashi: "Fluctuation effects in specific heat and magnetization of C-axis alligned(Bi,Pb)_2Sr_2Ca_2Cu_3O_x" Physica C. 219. 265-272 (1993)

[Publications] K.Matsuzaki: "Layered structure and superconducting properties of Ag-sheathed Bi_<1.84>Pb_<0.34>Sr_2Ca_2Cu_3O_y wires prepared by a combined jellyroll and hot extrusion technique" Jpn.J.Appl.Phys.64. (1994)

[Publications] Yoshitake: "Numerical Study on the Conductance of Normal-Superconductor Contacts" J.Phys.Soc.Jpn.62. 1844-1847 (1993)

[Publications] K.Tanaka: "Three-dimensional t-J model and cluster variation method" Physica B. (印刷中).

[Publications] K.Kishio: "Crystal Structure and Anisotropy of Iodine-Intercalated Bi_2Sr_2Ca_<n-1>Cu_nO_y" J.Superconductivity. 7. 117-121 (1994)

[Publications] M.Okuya: "Single Crystal Growth and Anisotropic Electrical Properties of(La_<1-x>Ca_x)_2CaCu_2O_6" J.Superconductivity. 7. 313-318 (1994)

[Publications] J.Shimoyama: "New Mercury-based Superconductor;(Hg,Cr)Sr_2CuO_y" Physica C. (印刷中).

[Publications] A.G.Aronov: "Gauge invariance and transport properties in superconductors above T_c" Phys.Rev.B. (in press). (1994)

[Publications] S.Ochiai: "Improvement of strain dependence of critical current of Ag/Bi2223 tapes by reducing oxide core fraction" Cryogenics. 33. 976-979 (1993)

[Publications] K.Osamura: "Phase diagram of Ln-Ba-Cu-O system(Ln=Lanthanide)" Z.Metallkde. 84. 532-538 (1993)

[Publications] K.Osamura: "Influence of Ag addition on J_c and mechanical properties of Ag/Bi2223 tapes" Advances in Superconductivity. 5. 689-692 (1993)

[Publications] S.Ochiai: "Estimation of strength distribution of Nb_3Sn in multifilamentary composite wire" J.Appl.Phys.74. 440-445 (1993)

[Publications] R.Ikeda: "Implications of Fluctuation Effects on Thermodynamic Quantities in Type II Superconductors" Physica B.

[Publications] X.G.Qiu: "Thermally activated flux dissipation in c-axis-oriented YBa_2Cu_3O_7/PrBa_2Cu_3O_7 multilayers" Phys.Rev.B. 47. 14519-14524 (1993)

[Publications] K.Matsuzaki: "High Temperature Superconducting Electronics(Microstructure and superconducting properties on hot extruded Tl- and Bi-based oxide)" OHMsha, 11 (1993)

[Publications] K.Watanabe: "Advances in High-T_c Superconductors(editted by J.J.Pouch,S.A.Alterovitz and R.R.Romanofsky)(Anisotropy and Dimensional Characteristic in CVD Route Y_1Ba_2Cu_3O_<7-d>)" Trans Tech Publications,Aedermannsdorf,Switzerland, 797 (1993)

北沢宏一東京大学, 工学部, 教授 (90011189)