• 한국초전도ㆍ저온공학회논문지
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• 제4권1호
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• pp.17-20
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• 2002

A complex single flux quantum(SFQ) circuit could be made up of various elementary cells such as JTL(Josephson transmission line), Splitter, XOR, DC/SFQ, SFQ/DC, T flip-flop, ‥‥, etc. In this work, we have designed and simulated a SFQ circuit, which consists of DC/SFQ, JTL and SFQ/DC, based on Nb/AlO$_{x}$Nb Josephson junction technology From the simulation, we could obtain the margins for various circuit parameters. And also we have successfully operated the circuit, which was fabricated with the same design, up to the input signal frequency of about 20 GHz.z.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2008년도 제35회 하계학술대회 초록집
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• pp.48-48
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• 2008

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2001년도 High Temperature Superconductivity Vol.XI
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• pp.5-5
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• 2001

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.185-188
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• 1999

Biepitaxial Y$_1Ba_2Cu_3O_{7-x}$ (YBCO) and La$_{0.2}Sr_{0.8}MnO_3$ (LSMO) thin films have been prepared on SrTiO$_3$ buffer layer and MgO seed layer grown on Al$_2O_3$(11${\bar{2}}$0)substrates by dc-sputtering with hollow cylindrical targets, respectively. We charaterized Josephson properties and significantly large magnetoresistance in YBCO and LSMO films with 45$^{\circ}$ grain boundary junction, respectively. The observed working voltage (I$_cR_n$) at 77 K in grain boundary junction was below 10${\mu}$V, which is typical I$_cR_n$ value of single biepitaxial Josephson junction. The field magnetoresistance ratio (MR) of LSMO grain boundary juncoon at 77K was enhanced to 13%, which it was significant MR value with high magnetic field sensitivity at a low field of 250 Oe. These results indicate that inserting the insulating layer instead of the grain boundary layer with metallic phase can be possible to apply a new SIS Josephson junction and a novel magnetic device using spin-polarized tunneling junction.

• 한국초전도ㆍ저온공학회논문지
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• 제23권2호
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• pp.6-9
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• 2021

단결정의 덩어리 시료로부터 박리된 NbSe₂와 FeSe 박막을 이용한 동종 초전도 vdW 접합을 만들고 저온전도측정을 통해 JJ 효과를 확인하였다. 각 물질의 초전도 틈을 측정하였으며 기존 결과와 잘 일치하는 것을 확인하였다. FeSe 접합의 경우 NbSe₂ 접합과 다르게 JJ가 구현되지 않는 경우가 다수 발생하는데 이는 NbSe₂와 구분되는 FeSe의 특성때문으로 보이며 일관성있는 JJ 구현을 위해서 저온 접합이나 접합 각도 의존성을 통한 향후 연구가 필요하다. 그럼에도 불구하고, 본 연구 결과는 FeSe 2차원 결정을 이용해 JJ가 잘 구현될 수 있음을 실험적으로 보인 첫 사례로서 그 의의를 갖는다.

• Progress in Superconductivity
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• 제1권2호
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• pp.146-150
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• 2000

Step edge Josephson junctions in c-axis oriented $YBa_2Cu_3O_7$ films were fabricated on $CeO_2$ buffered sapphire substrates. The step angle was controlled in the wide range of $20^{\circ}\sim75^{\circ}$ by the Ar ion milling technique. I-V curves of junction fabricated on the thickness ratio of $\sim$0.8 and the step angle of $35^{\circ}$ were exhibited RSJ-like behavior with $I_CR_N$ product of $\sim250{\mu}A$ and critical current density of $\sim2\times10^4A/cm^2$ at 77 K. Critical current of step edge junction was increased linearly with decreasing temperature but the normal resistance was almost constant. Total samples of step edge Josephson junction was satisfied a scaling behavior of $I_CR_N{\propto}(J_C)^{0.5}$.

• Progress in Superconductivity
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• 제2권2호
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• pp.81-85
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• 2001

Uniformity of critical currents of YBa$_2$Cu$_3$O$_{7}$ step-edge Josephson junctions on SrTiO$_3$(100) substrates have been studied at various step-line angles. 15 identical junctions were made in series on each substrate that has a long straight step-edge line. Step-line angles studied were 0$^{\circ}$, 15$^{\circ}$, 30$^{\circ}$, and 45$^{\circ}$with respect to the crystal major axes of the substrate. Scattering of junction critical currents among the junctions on the same substrate increased with the step-line angle. Current-voltage curves showed standard resistively-shunted-junction (RSJ) characteristics in most of the 0$^{\circ}$junctions. However, the number of junctions showing RSJ behavior decreased with increasing step-line angle. Variations of detailed microstructure of the step-edge among junctions, which are coupled with the d-wave symmetry of YBa$_2$Cu$_3$O$_{7}$, are believed to be the main cause for the nonuniformity in the critical current.ent.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.75-77
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• 2003

We have measured the escape rates of the Nb Josephson junction from its zero-voltage state. The critical current measurements were carried out in repeatedly sweeping the current-voltage characteristics of the junction with a current ramp. From the distribution of the critical current the escape temperature was determined by applying the thermal activation model.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.103-105
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• 2003

The high speed of RSFQ circuits is based on the self-resetting in the overdamped Josephson junctions. The SIS technology using Nb/A1$_2$O$_3$/Nb trilayer has been successfully adopted as a standard technology. However the newly suggested SINIS technology attracts interest because the junction itself is overdamped without any external shunt, and provides possibility of simplification of RSFQ circuit design and fabrication. In this paper we demonstrate RSFQ circuit fabrication process using SINIS technology.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2005년도 High Temperature Superconductivity Vol.XV
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• pp.47-47
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• 2005