2000 Fiscal Year Annual Research Report

伝導ノイズ及び密度ノイズ測定による高温超電導体ボルテックスのダイナミクスの研究

Research Project

Project/Area Number	12016202
Research Institution	The University of Tokyo
Principal Investigator	前田京剛東京大学, 大学院・総合文化研究科, 助教授 (70183605)
Co-Investigator(Kenkyū-buntansha)	北野晴久東京大学, 大学院・総合文化研究科, 助手 (00313164)
Keywords	洗濯板ノイズ / 伝導ノイズ / 動的相図 / moving Bragg glass / 局所密度ノイズ / 同時測定 / 干渉効果
Research Abstract	本研究の目的は,局所磁束密度ノイズ測定および,伝導ノイズ測定を主な手段として,高温超伝導体の磁束のダイナミクス,すなわち磁束系が運動している状態の集団としての性質を実験的に探り,ボルテックスデバイス開発の基礎を与えることであった.特に,ごく最近我々が,あらゆる超伝導体のなかで初めて発見した,「洗濯板ノイズ」を積極的に利用し,動的相図を明らかにすることを主目的とした。具体的には,本年度は以下の成果を得た。(1)ホール素子アレーを用いた局所密度ノイズ測定と伝導ノイズ測定を同一試料で同一実験ランで測定することに成功し,両者の詳細な比較をすることが出来た。実際,局所密度ノイズの極大を与える駆動力と,伝導ノイズの極大を与える駆動力は,わずかながら,明らかにことなっており,さらにそのあとに,洗濯板ノイズが見えることから,ピン止め状態-塑性フロー状態-コヒーレントフローの前駆としてのランダムな運動状態-コヒーレントフロー状態一理論的に未知の状態というボルテックスの動的状態の変遷をトレースすることに成功した。(2)Bi_2Sr_2CaCu_2O_y系で,外部交流と洗濯板周波数の干渉効果を見ることに成功した。干渉の幅などの駆動力依存性,交流振幅依存性を調べ,現在可能な理論と比較検討中である。近い将来,2次元ボルテックス系でもカオス,モードロッキングなどについて議論できるようになるであろう。

Research Products

(14 results)

All Other

All Publications (14 results)

[Publications] H.Kitano, et al.: ""Dynamics of vortices and quasiparticles in the mixed state of Bi_2Sr_2CaCu_2O_y";"Physica C. 335. 148-152 (2000)
[Publications] H.Kitano, et al.: ""Observation of collective excitation in Sr_<14-x>Ca_xCu_<24>O_<41>""Physica C. 341-348. 463-464 (2000)
[Publications] A.Maeda, et al.: ""Comparative study of thermal conductivity and surface impedance of Bi_2Sr_2CaCu_2O_y in the mixed state";"Physica C. 341-348. 1871-1872 (2000)
[Publications] Y.Togawa, et al.: ""Direct observation of the washboard noise of a driven vortex lattice in a high-temperature superconductor, Bi_2Sr_2CaCu_2O_y""Phys.Rev.Lett.. 85. 3716-3719 (2000)
[Publications] A.Maeda, et al.: ""Measurement of complex electrical conductivity of metallic powders in a sealed tube";"Jpn.J.Appl.Phys.. 39. 6459-6464 (2000)
[Publications] Y.Tsuchiya, et al.: ""High-frequency electromagnetic response in the mixed state of YBa_2Cu_3O_y.";"Physica C. (in press).
[Publications] H.Kitano, et al: ""Study of highly anisotropic conductivity and penetration depth of Bi_2Sr_2CaCu_2O_y by using a cavity perturbation technique";"in "Proceedings of the 12th International Symposium on Superconductivity(ISS'99)", Morioka, Japan, October 17-19,1999 (Springer-Verlag, Tokyo, 2000)26-28.. 26-28. (2000)
[Publications] Y.Tsuchiya, et al.: ""High frequency surface impedance measurement in the mixed state of Bi_2Sr_2CaCu_2O_y""in "Proceedings of the 12th International Symposium on Superconductivity(ISS'99)", Morioka, Japan, October 17-19, 1999 (Springer-Verlag, Tokyo, 2000)371-373.. 371-373 (2000)
[Publications] Y.Togawa, et al.: ""The conduction noise observered in Bi_2Sr_2CaCu_2O_y single crystal""in "Proceedings of the 12th International Symposium on Superconductivity(ISS'99)", Morioka, Japan, October 17-19, 1999 (Springer-Verlag, Tokyo, 2000)299-301.. 299-301 (2000)
[Publications] A.Maeda, et al.: ""Dynamics vs electronic states of vortx core high-Tc superconductors investigated by high-frequency impedance measurement";"Physica C. (in press).
[Publications] Y.Togawa, et al.: ""Conduction noise in Bi_2Sr_2CaCu_2O_y";"Physica C. (in press).
[Publications] S.Tajima, et al.: ""Optical responses of the stripe phase in high-Tc cuprates""Physica C. (in press).
[Publications] H.Kitano, et al.: ""Interlayer electrodynamics of Bi_2Sr_2CaCu_2O_y from the c-axis complex dielectric constant measurement";"Physica C. (in press).
[Publications] Y.Tsuchiya, et al.: ""Estimation of vortex viscosity from complex surface impedance measurement in the mixed state of YBa_2Cu_3O_y";"Physica C. (in press).

2000 Fiscal Year Annual Research Report

伝導ノイズ及び密度ノイズ測定による高温超電導体ボルテックスのダイナミクスの研究

Principal Investigator

前田 京剛 東京大学, 大学院・総合文化研究科, 助教授 (70183605)

Research Products

[Publications] H.Kitano, et al.: ""Dynamics of vortices and quasiparticles in the mixed state of Bi_2Sr_2CaCu_2O_y";"Physica C. 335. 148-152 (2000)

[Publications] H.Kitano, et al.: ""Observation of collective excitation in Sr_<14-x>Ca_xCu_<24>O_<41>""Physica C. 341-348. 463-464 (2000)

[Publications] A.Maeda, et al.: ""Comparative study of thermal conductivity and surface impedance of Bi_2Sr_2CaCu_2O_y in the mixed state";"Physica C. 341-348. 1871-1872 (2000)

[Publications] Y.Togawa, et al.: ""Direct observation of the washboard noise of a driven vortex lattice in a high-temperature superconductor, Bi_2Sr_2CaCu_2O_y""Phys.Rev.Lett.. 85. 3716-3719 (2000)

[Publications] A.Maeda, et al.: ""Measurement of complex electrical conductivity of metallic powders in a sealed tube";"Jpn.J.Appl.Phys.. 39. 6459-6464 (2000)

[Publications] Y.Tsuchiya, et al.: ""High-frequency electromagnetic response in the mixed state of YBa_2Cu_3O_y.";"Physica C. (in press).

[Publications] Y.Tsuchiya, et al.: ""High frequency surface impedance measurement in the mixed state of Bi_2Sr_2CaCu_2O_y""in "Proceedings of the 12th International Symposium on Superconductivity(ISS'99)", Morioka, Japan, October 17-19, 1999 (Springer-Verlag, Tokyo, 2000)371-373.. 371-373 (2000)

[Publications] Y.Togawa, et al.: ""The conduction noise observered in Bi_2Sr_2CaCu_2O_y single crystal""in "Proceedings of the 12th International Symposium on Superconductivity(ISS'99)", Morioka, Japan, October 17-19, 1999 (Springer-Verlag, Tokyo, 2000)299-301.. 299-301 (2000)

[Publications] A.Maeda, et al.: ""Dynamics vs electronic states of vortx core high-Tc superconductors investigated by high-frequency impedance measurement";"Physica C. (in press).

[Publications] Y.Togawa, et al.: ""Conduction noise in Bi_2Sr_2CaCu_2O_y";"Physica C. (in press).

[Publications] S.Tajima, et al.: ""Optical responses of the stripe phase in high-Tc cuprates""Physica C. (in press).

[Publications] H.Kitano, et al.: ""Interlayer electrodynamics of Bi_2Sr_2CaCu_2O_y from the c-axis complex dielectric constant measurement";"Physica C. (in press).

[Publications] Y.Tsuchiya, et al.: ""Estimation of vortex viscosity from complex surface impedance measurement in the mixed state of YBa_2Cu_3O_y";"Physica C. (in press).

前田京剛東京大学, 大学院・総合文化研究科, 助教授 (70183605)