マイクロ波空洞共振器を用いた強相関ソフトマテリアルのマクロ相分離の研究

• Project/Area Number: 14045215
• Research Category: Grant-in-Aid for Scientific Research on Priority Areas
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering
• 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)
• Project Period (FY): 2002 – 2003
• Project Status: Completed (Fiscal Year 2003)
• Budget Amount: ¥1,800,000 (Direct Cost: ¥1,800,000); Fiscal Year 2003: ¥1,000,000 (Direct Cost: ¥1,000,000); Fiscal Year 2002: ¥800,000 (Direct Cost: ¥800,000)
• Keywords: 粉末試料 / マイクロ波電気伝導度 / DNA / フラーレン / 高周波電気伝導 / 非接触 / 電磁波の生体に対する影響 / 分離回収 / マイクロ波 / 高温超電導体 / クリーン / 磁束量子 / フラックスフロー / 不純物添加 / 非線形性 / 表面インピーダンス

Research Abstract

1)「強相関ソフトマテリアル」の動特性を粉末試料に対して行えることを目的として,様々な条件下で、マイクロ波を用いた非接触の方法により,物質の複素電気伝導度を正確に求める手法の確立に向けて研究をおこなった。この方法を応用して,以下で具体例成果を得た。現在これを,プロトン互変異性固体の誘電特性評価へと応用している。
2)フラーレン系の導電性評価:上記の方法をアンモニア置換フラーレン系に適用し,同系で,初めて電気伝導度を評価することに成功した。この方法を,さらに,K_4C_<60>系(電気的性質がほとんど評価されていない)に適用し,同系が絶縁体的であることを明らかにした。
3)DNAの交流伝導度:低周波電磁界が生体に影響を与えるか否か,非常に興味が持たれているが,現時点で,科学的なデータがない。もしそのような効果があれば,何らかの変化がDNAの伝導特性に現れることが期待される。直流の伝導特性はDNA中の欠陥などに非常に敏感であるのに対して,非接触交流伝導度測定は相対的にそのような欠陥に鈍感であるというメリットがある。上述の方法をDNA粉末に対して適用し,DNAのパイ結合間のホッピングによる電気伝導度を求めることに成功した。
4)本研究の当初の目標は,(1)強相関ソフトマテリアルを構成する代表的な機能分子ユニットを適切な溶媒と供にマイクロ波・ミリ波空洞共振器内に挿入し,機能分子が,その導電性・誘電性に応じて,空洞共振器内の交流電場または交流磁場の空間分布に対応した空間分布を取るための条件を調べ,(2)強相関ソフトマテリアルを構成する機能分子ユニットを高周波電磁波を用いて分離回収するための基礎物性を評価することであった。我々が開発した測定手法を用いれば,この様な目的にも充分適用可能であると考える。今後も,当初の目的実現に向けて研究を継続してゆきたい。

Research Products

• [Publications] R.Inoue: "Double sphere model in the enclosed cavity perturbation"J.Appl.Phys.. 93. 2736-2745 (2003)
• [Publications] A.Maeda: "Sliding conduction by the quasi one-dimentional charge-ordered state in Sr_<14-x>Ca_xCu_<24>O_<41+δ>"Physical Review B. 67. 115115-115119 (2003)
• [Publications] K.Kinoshita: "Millimeter wave and microwave electrodynamic spectroscopy of YBa_2(Cu_<1-x>Zn_x)_3O_y in the Meissner and mixed state"Physica C. 388-389. 417-418 (2003)
• [Publications] H.Kitano: "Nonlinear conductivity in the slightly hole-doped Sr_<14-x>Ca_xCu_<24>O_<41> ladder compounds"Physica C. 388-389. 231-232 (2003)
• [Publications] K.Iwaya: "Electronic state of NbSe_2 investigated by STM/STS"Physica B. 329-333. 1598-1599 (2003)
• [Publications] A.Maeda: "Dynamic phase diagram of vortices in high-Tc superconductors determined by experimental studies"Physica B. 329-333. 1346-1347 (2003)
• [Publications] R.Inoue: "The inverse analysis of the enclosed cavity perturbation technique"Physica B. 329-333. 1546-1547 (2003)
• [Publications] Y.Togawa: "Dynamic phase diagram of driven vortices in Bi_2Sr_2CaCu_2O_y"J.Low Temp.Phys.. 131. 907-911 (2003)
• [Publications] H.Kitano: "Microwave conductivity of superconducting and insulating fullerides"J.Low Temp.Phys. 131. 1251-1258 (2003)
• [Publications] A.Maeda: "Effect of impurities on the electronic structure of vortex core investigated by microwave surface impedance measurement"J.Low Temp.Phys. 131. 969-973 (2003)
• [Publications] Y.Iwasa: "Effect of impurities on the electronic structure of vortex core investigated by microwave surface impedance measurement"Physica B. 388-389. 615-616 (2003)
• [Publications] T.Hanaguri: "An instrument for low-and variable-temperature-wave surface impedance"Rev.Sci.Instrum. 74. 4436-4441 (2003)
• [Publications] A.Maeda: "Study of kinetic friction of solid using driven lattice of quantized vortex in high-temperature superconductors -a new route to study microscopic tribology"Proc.1^<st> Meeting on Applied Physics, Badajoz, Spain. (in press).
• [Publications] K.Kinoshita: "Impurity effect on the electronic state of the vortex core in the mixed state of Yba_2Cu_3O_y"Physica C. (in press).
• [Publications] H.Kitano: "Frequency dependent microwave conductivity of La_<2-x>Sr_xCuO_4 thin films"Physica C. (in press).
• [Publications] H.Kitano: "Microwave conductivity of fullerene intercalation compounds : Mott transition driven by the orthorhombic distortion"Proc.Fullerenes, Nanotubes, and Carbon Nanoclusters Symposia, France.2003. 469-473 (2003)
• [Publications] R.Inoue: "A nondestructive method of measureing dielectric properties of substrate at microwave and millimeter-wave frequencies using an open-ended coaxial resonator probe"Proc.1^<st> Meeting on Applied Physics, Badajoz, Spain. (in press).
• [Publications] R.Inoue: "Investigation of a new technique to measure large dielectric constant at microwave frequencies using the enclosed cavity perturbation method"Proc.1^<st> Meeting on Applied Physics, Badajoz, Spain. (in press).
• [Publications] R.Inoue: "Geometrical factors in the measurement of high temperature superconductors by the enclosed cavity perturbation technique"Proc.of 2003 Asia-Pacific Microwave Conference (APMC'03), Seoul, extended abstract. 3. 2040-2043 (2003)
• [Publications] A.Maeda et al.: "Vortices in high Tc superconductors""Vortex Electronics and SQUIDs", edited by T. Kobayashi. (in press).
• [Publications] A.Maeda et al.: "Dynamics of vortices in high-Tc superconductors investigated by density and conduction noise measurements"Sutudies of High Temperature Superconductors, edited by A. Narlikar, Vol.41, Chap.10 (Nova Science Publishers, NY2002). 247-274 (2002)
• [Publications] A.Maeda et al.: "Location-sensitive measurement of the local fluctuation of driven vortex density in Bi_2Sr_2CaCu_2O_y"Physical Review B. 65. 54506-54516 (2002)
• [Publications] H.Kitano et al.: "Evidence for insulating behavior in the electric conduction (NH_3)K_3C_<60> systems"Phys. Rev. Lett.. 88. 96401-96404 (2002)
• [Publications] A.Maeda, Y.Togawa, H.Kitano: "An experimental approach to understand dynamical phase diagram of driven vortices of high-Tc superconductors"Pnysica C. 369. 177-181 (2002)
• [Publications] H.Kitano, A.Maeda: "Comment on "Anomalous dielectric response in the π-d correlated metallic state of λ-(BEDT-TSF)_2FeCl_4"J. Phys. Soc. Japan. 71. 666-667 (2002)
• [Publications] K.Takaki et al.: "Effects of superconducting gap anisotropy on the flux flow resistivity in Y(Ni_<1-x>Pt_x)_2B_2C"Phys. Rev. B. 66. 184511-184515 (2002)
• [Publications] K.Kinoshita et al.: "Millimeter wave and microwave electrodynamic spectroscopy of YBa_2(Cu_<1-x>Zn_x)_3O_y in the Meissner and mixed state"Physica C. (in press).
• [Publications] H.Kitano et al.: "Nonlinear conductivity in the slightly hole-doped Sr_<14-x>Ca_xCu_<24>O_<41> ladder compounds"Physica C. (in press).
• [Publications] K.Iwaya et al.: "Electronic state of NbSe_2 investigated by STM/STS"Physica C. (in press).
• [Publications] A.Maeda, Y.Togawa, H.Kitano: "Dynamic phase diagram of vortices in high-Tc superconductors determined by experimental studies"Physica C. (in press).
• [Publications] R.Inoue, H.Kitano, A.Maeda: "The inverse analysis of the enclosed cavity perturbation technique"Physica C. (in press).
• [Publications] Y.Togawa, H.Kitano, A.Maeda: "Dynamic phase diagram of driven vortices in Bi2Sr2CaCu2Oy"J. Low Temp. Phys.. (in press).
• [Publications] K.Kinoshita et al.: "Microwave conductivity of superconducting and insulating fullerides"J. Low Temp. Phys.. (in press).
• [Publications] A.Maeda et al.: "Effect of impurities on the electronic structure of vortex core investigated by microwave surface impedance measurement"J. Low Temp. Phys.. (in press).