• 제목/요약/키워드: ${Bi_2}{Sr_2}Ca{Cu_2}{O_{8+x}}$

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Oscillatory Josephson-Vortex Resistance in Stacks of $Bi_{2}Sr_{2}CaCu_{2}O_{8+x}$ Intrinsic Josephson Junctions

  • 최재현;배명호;이후종;김상제
    • Progress in Superconductivity
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    • 제7권1호
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    • pp.17-21
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    • 2005

  • We report the oscillation of the Josephson vortex-flow resistance in the rectangular stacks of $Bi_{2}Sr_{2}CaCu_{2}O_{8+x}$(Bi-2212) intrinsic Josephson junctions (IJJs). Apiece of Bi-2212 single crystal containing a few tens of IJJs was sandwiched between two gold electrodes and fabricated into a rectangular shape with the typical lateral size of about $1.5{\times}10\;{\mu}m^2$, using e-beam lithography and focused ion-beam etching techniques. In a tesla-range magnetic field applied in parallel with the junction planes, the oscillation of the Josephson vortex flow resistance was observed at temperatures near 60 K. The oscillation results from the interplay between the triangular Josephson vortex lattice and the potential barrier at the boundary of a single crystal. The oscillatory magnetoresistance for different bias currents, external magnetic fields, and the tilt-angles provides useful information on the dynamics of the coupled Josephson-vortex lattice system.

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Phase transition of (Bi, Pb)-2223 superconductor induced by Fe3O4 addition

  • Ko, Y.J.;Oh, J.Y.;Song, C.Y.;Yang, D.S.;Tran, D.H.;Kang, B.
    • 한국초전도ㆍ저온공학회논문지
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    • 제21권4호
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    • pp.1-5
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    • 2019

  • We investigated the effect of Fe3O4 addition on the critical temperature of (Bi, Pb)-2223 polycrystalline samples. Bi1.6Pb0.4Sr2Ca2Cu3O10+δ + x wt. % Fe3O4 (x = 0.0, 0.2, 0.4, 0.6, and 0.8) samples were prepared by using a solid-state reaction method. The analysis of X-ray diffraction data indicates that as Fe3O4 is added, dominant phase of the sample changes from Bi-2223 to Bi-2212 with an increasing Bi-2201 phase. The transition temperature of the samples drastically decreased with the Fe3O4 addition. The resistance data of samples with x = 0.2 and 0.4 showed a double transition indicating a coexistence of Bi-2223 and Bi-2212 phase while the samples with x = 0.6 and 0.8 showed a single transition with a semiconducting behavior. This phase transition may originate from changes in local structure of the Bi-2223 system by Fe3O4 addition. Analysis of the pair distribution function of the Cu-O pair in the CuO2 plane calculated from extended X-ray absorption fine structure data revealed that the oxygen coordination of copper ion changes from CuO4 planar type (x = 0.0 - 0.4) to CuO5 pyramidal type (x = 0.6, 0.8). The correlated Debye-Waller factor, providing information on the atomic disorder within the CuO2 plane, shows an inverse relation to the coordination number. These results indicate that addition of Fe3O4 changes the oxygen distribution around Cu in the CuO2 plane, causing a phase transition from Bi-2223 to more stable Bi-2212/Bi-2201 phases.

  • https://doi.org/10.9714/psac.2019.21.4.001 인용 PDF KSCI