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2001 Fiscal Year Final Research Report Summary

Search for New Quantum Effects in Superconducting Vortices

Research Project

Project/Area Number 12450003
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Applied materials science/Crystal engineering
Research InstitutionThe University of Tokyo

Principal Investigator

HANAGURI Tetsuo  Graduate School of Frontier Sciences, The University of Tokyo, Professor, 大学院・新領域創成科学研究科, 助教授 (40251326)

Co-Investigator(Kenkyū-buntansha) MAEDA Atsutaka  Graduate School of Frontier Sciences, The University of Tokyo, Associate Professor, 大学院・総合文化研究科, 助教授 (70183605)
Project Period (FY) 2000 – 2001
KeywordsFlux flow resistivity / Electronic specific heat coefficient / Surface Impedance / Scanning tunneling microscopy / High-T_c superconductors / NbSe_2 / YNi_2B_2C
Research Abstract

In this study, we examined the electronic states of vortex states of various clean superconductors such as high-T_c cuprates, NbSe_2 and YNi_2B_2C by utilizing the surface impedance measurements, specific heat measurements and scanning tunneling microscopy (STM).
We succeeded in building a surface impedance measurement apparatus which works at very low temperatures down to 0.5K under magnetic fields. By using this apparatus, we measured flux flow resistivity of YBa_2Cu_3O_y and strongly anisotropic s-wave superconductor YNi_2B_2C. From the analysis, we found that the electronic state of vortex core of YBa_2Cu_3O_y is in the so-called "moderately clean" regime and vortex core is somewhat different from classical normal state core. In YNi_2B_2C, flux flow resistivity was almost twice as large as that expected from the conventional Bardeen Stephen model. This result indicates that the energy dissipation in the vortex core is strongly affected by the anisotropy of the superconducting gap.
We also measured the magnetic field H dependence of electronic specific heat coefficients of various NbSe_2 crystals and found that the quasi-particle density of states (QPDOS) deviates from conventional H-linear behavior with increasing sample purity. From measurements on the sample containing columnar defects introduced by heavy ion irradiation, we found that the QPDOS anomaly is brought by quasi particles outside of vortex cores. From the comparative resistivity measurements and STM observations, we conclude that the QPDOS anomaly is strongly correlated with the evolution of charge-density wave which coexists with superconductivity.

  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] Y.Tsuchiya: "Electronic state of vortices in YBa_2Cu_3O_y investigated by complex surface impedance measurements"Phys. Rev. B. 63. 184517 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Takaki: "Effects of superconducting gap anisotropy on the flux flow resistivity in Y(Ni_<1-x>Pt_x)_2B_2C"Phys. Rev. B. 66. 184511 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Hanaguri: "Anomaly of quasi-particle density of states in the vortex state of NbSe_2"Physica B. (印刷中).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Iwaya: "Electronic state of NbSe_2 investigated by STM/STS"Physica B. (印刷中).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Y.Kohsaka: "Real Space Imaging of the Electronic States in Underdoped Ca_<2-x>Na_xCuO_2CI_2 Single Crystals"J. Low Temp. Phys.. (印刷中).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Y. Tsuchiya, K. Iwaya, K. Kinoshita, T. Hanaguri, H. Kitano, A. Maeda, K. Shibata, T. Nishizaki and N. Kobayashi: "Electronic state of vortices in YBa_2Cu_3O_y investigated by complex surface impedance measurements"Phys. Rev. B. 63. 184517 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K. Takaki K., A. Koizumi, T. Hanaguri, M. Nohara, H. Takagi, K. Kitazawa, Y. Kato, Y. Tsuchiya, H. Kitano and A. Maeda: "Effects of superconducting gap anisotropy on the flux flow resistivity in Y(Ni_<1-x>Pt_x)_2B_2C"Phys. Rev. B. 66. 184511 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T. Hanaguri, A. Koizumi, K. Takaki, M. Nohara, H. Takagi and K. Kitazawa: "Anomaly of quasi-particle density of states in the vortex state of NbSe_2"Physica B. (in press).

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K. Iwaya, T. Hanaguri, A. Koizumi, K. Takaki, A. Maeda and K. Kitazawa: "Electronic state of NbSe_2 investigated by STM/STS"Physica B. (in press).

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Y. Kohsaka, T. Hanaguri, K. Kitazawa, M. Azuma, M. Takano and H. Takagi: "Real Space Imaging of the Electronic States in Underdoped Ca_<2-x>Na_xCu0_2Cl_2 Single Crystals"J. Low Temp. Phys.. (in press).

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2003-09-17  

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