Progress in Superconductivity

The Korean Superconductivity Society (한국초전도학회)
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Effect of weak interlayer coupling on critical fluctuation in high $T_c$ superconductors

  • Kim, Jin-Tae (Korea Research Institute of Standards and Science) ;
  • Kang, W.N. (National Creative Research Initiative Center for Supercondutivity, Department of Physics, Pohang University of Science and Technology) ;
  • Chung, S.H. (Korea Research Institute of Standards and Science) ;
  • Ha, D.H. (Korea Research Institute of Standards and Science) ;
  • Yoo, K.H. (Korea Research Institute of Standards and Science) ;
  • Kim, M.S. (National Creative Research Initiative Center for Supercondutivity, Department of Physics, Pohang University of Science and Technology) ;
  • Lee, Sung-Ik (National Creative Research Initiative Center for Supercondutivity, Department of Physics, Pohang University of Science and Technology) ;
  • Park, Y.K. (Korea Research Institute of Standards and Science) ;
  • Park, J.C. (Korea Research Institute of Standards and Science)
  • Published : 1999.08.15
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Abstract

The magnetization and/or resistivity of high $T_c$ superconductors ($YBa_2Cu_3O_{7-\delta}$(YBCO) single crystal, $Bi_2Sr_2CaCu_2O_8$ (Bi-2212) single crystal, $Tl_2Ba_2CaCu_2O_8$ (Tl-2212) film, $HgBa_2Ca_2Cu_3O_8$ (Hg-1223) film) have been measured as a function of magnetic field H and temperature T. The extracted fluctuation part of the magnetization and conductivity exhibits a critical behavior consistent with the three-dimensional XY model. The dynamic critical exponent z does not sensitively vary with a type of the superconductors. The value of z ranges from 1.5 to $1.8{\pm}0.1$. However, the static critical exponent ${\nu}$ is the most largely increased in Tl-2212 that has a weaker interlayer coupling strength than YBCO; the value of ${\nu}$ is 0.669, 0.909, 1.19, and 1.338 for YBCO, Bi-2212, Hg-1223, and Tl-2212 respectively. The results indicate that the weak interlayer coupling along the c-axis of high $T_c$ superconductors near $T_c$ does not influence the dynamic critical exponent z (the same value of superfluid $^4He$), but significantly increases the static critical exponent ${\nu}$.

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