Progress in Superconductivity

The Korean Superconductivity Society (한국초전도학회)
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Domination of glassy and fluctuation behavior over thermal activation in vortex state in $MgB_2$ thin film

$MgB_2$ 박막에서의 열적 활성화에 비해 두드러진 볼텍스 유리화 및 열적 요동현상의 연구

  • Kim, Heon-Jung (Natinal Creative Research Initiative Center for Superconductivity, Department of Physics, Pohang University of Science and Technology) ;
  • W. N. Kang (Natinal Creative Research Initiative Center for Superconductivity, Department of Physics, Pohang University of Science and Technology) ;
  • Kim, Hyeong-Jin (Natinal Creative Research Initiative Center for Superconductivity, Department of Physics, Pohang University of Science and Technology) ;
  • Park, Eun-Mi (Natinal Creative Research Initiative Center for Superconductivity, Department of Physics, Pohang University of Science and Technology) ;
  • Kim, Kijoon H. P. (Natinal Creative Research Initiative Center for Superconductivity, Department of Physics, Pohang University of Science and Technology)
  • Published : 2001.01.01
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Abstract

We have investigated the mixed-state magnetoresistance of high quality c-axis-oriented MgB2 thin film for magnetic field from 0.5 T to 5.0 T, applied normal to ab-plane. The temperature dependence of magnetoresistance was well described by vortex glass and fluctuation theories for different temperature regimes. We observed glassy exponent of v(z-1)~3 and upper critical field of $H_{c2}$(0)~35 T, which is consistent with previous data obtained from direct $H_{c2}$(0) measurements. Interestingly, the thermally activated flux flow region was observed to be very narrow, suggesting that the pinning strength of this compound is very strong. This finding is closely related to the recent reports that the bulk pinning is dominant in $MgB_2$and the critical current density of $MgB_2$ thin film is very high, comparable to that of cuprate superconductor. The present results further suggest that $MgB_2$is beneficial to technical applications.ons.

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