• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.29-29
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• 2007

• ETRI Journal
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• v.18 no.4
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• pp.301-313
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• 1997

We have found that in the ballistic electron transport in a ring structure, the junction-backscattering contribution is critical for all the major features of the Aharonov-Bohm-type interference patterns. In particular, by considering the backscattering effect, we present new and clear interpretation about the physical origin of the secondary minima in the electrostatic Aharonov-Bohm effect and that of the h/2e oscillations when both the electric and magnetic potentials are present. We have devised a convenient scheme of expanding the conductance by the junction backscattering amplitude, which enables us to determine most important electron paths among infinitely many paths and to gain insight about their contributions to the interference patterns. Based on the scheme, we have identified various interesting interference phenomena in the ballistic ring structure and found that the backscattering effect plays a critical role in all of them.

• ETRI Journal
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• v.16 no.2
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• pp.1-13
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• 1994

We have identified two new features related to the coherent transport in the mesoscopic loop structure of aluminum wire, including the autocorrelation of the conductance fluctuations beyond $B_c$ and fine structure in the low-field magnetoresistance curve in the superconducting transition regime, which, to the best of our knowledge, have not been reported in the literature. Since the electrons in Al have a phase coherence length larger than $1\;{\mu}m$ at or below T = 3K, which is comparable to the dimensions of the structure, the wave nature of the electronic transport has been clearly observed: the universal conductance fluctuations, the Aharonov-Bohm oscillations, and the Altshuler-Aronov-Spivak oscillations. Due to the transition of Al to a superconducting state at T = 1.3 K, the coherent phenomena of Cooper pairs, i.e., the Little-Parks oscillations, have also been observed.

• Progress in Superconductivity and Cryogenics
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• v.21 no.4
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• pp.13-18
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• 2019

Superconducting junctions of topological insulator (TI) are expected to host Majorana bound state, which is essential for developing topological quantum information devices. In this study, we fabricated Josephson junctions (JJs) made of Sb-doped Bi2Se3 TI nanoribbon and PbIn superconducting electrodes. In the normal state, the axial magnetoresistance data exhibit periodic oscillations, so-called Aharonov-Bohm oscillations, due to a metallic surface state of TI nanoribbon. At low temperature of 1.5 K, the TI JJ reveals the superconducting proximity effects, such as the critical current and multiple Andreev reflections. Under the application of microwave, integer Shapiro steps are observed with satisfying the ac Josephson relation. Our observations indicate that highly-transparent superconducting contacts are formed at the interface between TI nanoribbon and conventional superconductor, which would be useful to explore Majorana bound state in TI.