Effect of columnar defects on the irreversibility line in pristine and iodine-intercalated Bi$_2$Sr$_2$CaCu$_2$O$_{8+{\delta}} single crystals

  • Kim, Ki-Joon (National Creative Research Initiative Center for Superconductivity and Department of Physics, Pohang University of Science and Technology) ;
  • Kim, Mun-Seog (National Creative Research Initiative Center for Superconductivity and Department of Physics, Pohang University of Science and Technology) ;
  • Choi, Jae-Hyuk (National Creative Research Initiative Center for Superconductivity and Department of Physics, Pohang University of Science and Technology) ;
  • Kang, W.N. (National Creative Research Initiative Center for Superconductivity and Department of Physics, Pohang University of Science and Technology) ;
  • Lee, Sung-Ik (National Creative Research Initiative Center for Superconductivity and Department of Physics, Pohang University of Science and Technology) ;
  • Ha, Dong-Han (Korea Research Institute of Standards and Science) ;
  • Kim, Dong-Ho (Departemt of Physics, Yeungnam University)
  • Published : 2000.08.16

Abstract

We have investigated the influence of columnar defects (CD) on the vortex dynamics in pristine and iodine-intercalated Bi$_2$Sr$_2$CaCu$_2$O$_{8+{\delta}} single crystals from do SQUID magnetization measurements. Especially, the temperature dependence of the irreversibility fields, H$_{irr}$(T), were studied. Anisotropy ratio ${\gamma}$, estimated from the fitting to the 2-dimensional melting model (A. Schilling et al., Phys. Rev. Lett. 71 1899 (1993)) in higher fields than the matching field B$_{\phi}$ at low temperature region, turns out to be decreased by the iodine-intercalation and additionally by the heavy-ion irradiation.

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