• 한국초전도학회:학술대회논문집
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• v.14
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• pp.56-56
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• 2004

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.178-184
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• 1999

We have measured I-V characteristics of Bi$_2Sr_2CaCu_2O_{8+{\delta}}$ mesa containing a small number of intrinsic stacked Josephson junctions in a magnetic field. We fabricated mesa with an area of 40${\times}$40 ${\mu}$m$^2$ containing 3${\sim}$20 intrinsic junctions. We applied magnetic field perpendicular to He CuO$_2$ planes up to 5T. We observed flux-flow branches and flux-flow steps in the I-V characteristics which might be due to collective motion of Josephson vortices in the long junction limit. In a parallel field, critical current I$_c$ varies as I$_c$(B) ${\sim}$ exp(-B/B$_0$), where B$_0$ is about 2T, which is consistent with the theoretical model. DC and AC intrinsic Josephson effects are also discussed.

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.47-47
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• 2006

• 한국초전도학회:학술대회논문집
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• v.14
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• pp.62-62
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• 2004

• 한국초전도학회:학술대회논문집
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• v.14
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• pp.63-63
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• 2004

• 한국초전도학회:학술대회논문집
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• v.15
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• pp.44-44
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• 2005

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.9-14
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• 2000

We report on the novel nonequilibrium nlicrowave emission from quasiparticle-injected high-Tc superconductors. The phenomena have been observed for the current-injected YBCO/I/Au or BSCCO/I/Au thin-film tunnel junctions and BSCCO single-crystal intrinsic Josephson mesa junction samples. For the thin-film tunnel junctions, the emitted radiation appears as broadband. For the intrinsic BSCCO mesa samples, the radiation appears as three different modes of emissions depending on the bias point in the hysteretic current-voltage characteristics; Josephson-emission, nonequilibrium broad emission and sharp coherent microwave emission. The results were interpreted by the Josephson plasma excitation model due to quasiparticle injection.

• Progress in Superconductivity
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• v.4 no.1
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• pp.59-63
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• 2002

10-V Josephson junction array arranged in 8 parallel stripline paths was fabricated using self-aligning and reactive ion etching techniques. These techniques were introduced in detail with aim of obtaining high-quality junctions. The array has 18,184 Josephson junctions with the area of $12\mu\textrm{m}$$\times$$38\mu\textrm{m}$. The gap voltage and minimum critical current density were about 2.7 ㎷ and ／$23 A\textrm{cm}^2$, respectively. And the critical current density and leakage current at 5 volt were about 27 $A／\textrm{cm}^2$ and $5\mu\textrm{A}$, respectively When operated in the frequency range of 76-88 ㎓, the away generated constant voltage steps up to 14-19 V. The step size near 10-V was more than 7 $\mu\textrm{A}$.

• Progress in Superconductivity
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• v.4 no.1
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• pp.64-67
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• 2002

The attenuation of millimeter waves (70-100 ㎓) propagating along Josephson Junction stripline had been measured by pattern recognition near gap voltage and proximity current bump. Test series arrays of 2000, 3000, and 4000 Josephson junctions with the area of $12\mu\textrm{m}$$\times$ $38\mu\textrm{m}$ had two sub-arrays with 50 Junctions at both ends. The arrays were fabricated with and without applying a plasma nitridation process to Nb ground plane. The effects of a nitridationprocess measured by the pattern recognition near gap voltage and proximity current bump were about 1.3-1.7 ㏈ and 1.6-1.8 ㏈, respectively. This means that the last sub-arrays with a nitridation process receive 26-34% more power than those without a nitridation process.

• Progress in Superconductivity and Cryogenics
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• v.23 no.2
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• pp.6-9
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• 2021

Heterostructures fabricated by various combinations of van der Waals (vdW) materials enable us to investigate disorder-free physical properties and realize novel functional devices. Superconducting vdW junctions have attracted a lot of attention because of its simple structure without a barrier layer. In superconducting vdW junction, without extra fabrication effort, a natural barrier can be formed, whose character is sensitive to distance and angle of lattice between two superconducting vdW materials. Using high-quality single crystals and the dry transfer technique, we fabricated the vertically stacked NbSe₂/NbSe₂ and FeSe/FeSe vdW junctions and investigated their Josephson junction properties. We found that in the FeSe junctions, Josephson coupling is extremely sensitive to the fabrication conditions, in contrast to the NbSe₂ junctions. We attributed this distinct character of the FeSe junctions to surface instability and small Fermi surface of FeSe.