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1.
Microwave induced d.c. voltage due to inverse a.c. Josephson effect has been observed across bulk samples of Y-Ba-Cu-O and Y-Ba-Sr-Cu-O. The d.c. voltage is found to vary with microwave power, frequency and also with small external magnetic fields. Although the resistivity curve of Y-Ba-Cu-O does not show any appreciable resistance drop around 230 K, the microwave induced d.c. voltage due to the inverse a.c. Josephson effect has been found to exist upto 230 K. The resistivity behaviour of Y-Ba-Sr-Cu-O shows a sharp resistivity drop above 230 K. In this sample the inverse Josephson effect is found to exist upto +26 °C, indicating the presence of a phase having a superconducting onset around this temperature. 相似文献
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在s波超导体绝缘层dx2-y2波超导体结(sId)中,考虑到结界面粗糙散射,运用BogoliubovdeGennes(BdG)方程和FurusakiTsukada(FT)电流公式,计算超导结中的准粒子传输系数和直流Josephson电流.结果表明:sId超导结的直流Josephson电流随温度以及结两侧的相位差变化的关系曲线强烈地依赖于d波超导体的晶轴方位;结界面的粗糙散射对Josephson电流有抑制作用
关键词:
s/I/d超导结
dx2-y2波超导体
直流Josephson电流 相似文献
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在 s波超导体 /铁磁绝缘层 / d波超导体 Josephson结 (s/ FI/ d)中 ,考虑结界面铁磁绝缘层的磁散射和粗糙散射情况下 ,运用 Bd G方程和 FT的电流公式计算准粒子的输运系数及 s/ FI/ d结的直流 Josephson电流与温度 T、结两侧的相位差之间的关系。研究表明 :结界面的磁散射和粗造散射均抑制结中准粒子的 Andreev反射 ,降低了流过 s/ FI/ d结的直流 Josephson电流 ,直流Josephson电流 I随温度 T、相位差φ的变化曲线强烈地依赖于 d波超导体的晶轴方位 相似文献
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M. A. Tarasov E. A. Stepantsov M. Naito A. Tsukada D. Winkler A. S. Kalabukhov M. Yu. Kupriyanov 《Journal of Experimental and Theoretical Physics》2007,105(3):636-641
The possibility of preparing bicrystalline Josephson junctions and bolometers based on superconducting MgB2 on specially prepared bicrystalline MgO substrates is investigated. Microbridges 0.85–6.00 μm in width, intersecting the bicrystalline interface, are formed in epitaxial bicrystalline MgB2 films grown on these substrates. It is found that annealing of bicrystalline samples in oxygen leads to a systematic decrease in the critical current, an increase in the temperature width of the superconducting transition region, and to an improvement of the current-voltage (IV) characteristic, which becomes close in shape to the IV characteristic of a Josephson junction. The response of such a junction to radiation at a frequency of 110 GHz with an amplitude attaining 0.5 mV is measured. 相似文献
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R. De Luca 《Physics letters. A》2011,375(24):2441-2443
The current-phase relations of a double-barrier Josephson junction with a thin intermediate electrode show deviations from the usual sinusoidal dependence of a single Josephson junction. The skewness of these curves can be analytically found for small values of the coupling between the two outer electrodes of the double-barrier Josephson junction. 相似文献
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A. S. Malishevskii V. P. Silin S. A. Uryupin S. G. Uspenskii 《Physics of the Solid State》2004,46(9):1591-1603
For a Josephson junction magnetically coupled to the superconducting waveguides enclosing it, solutions to the equation for the difference of the Cooper pair phases over the Josephson junction are found and the corresponding magnetic field values are calculated. Two gaps imposing an upper limit for the vortex velocity are found for free vortices (moving without dissipation). Existence conditions are found for fast vortices in the two high-velocity allowed regions. The dependence of the transport current on vortex velocity is established in cases where the current flows through the Josephson junction only or through the entire structure. A reverse current phenomenon is discovered in which vortices inside allowed velocity regions move opposite to the usual direction. 相似文献
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D. A. Ryndyk 《Journal of Experimental and Theoretical Physics》1999,89(5):975-985
This paper examines the time-dependent Josephson effect in systems of tunnel superconducting junctions and in layered superconductors
(the intrinsic Josephson effect) with allowance for nonequilibrium superconductivity effects. Kinetic and quasihydrodynamic
equations are derived that describe self-consistently the dynamics of Josephson phases and nonequilibrium quasiparticles.
It is found that the state of nonequilibrium between the layers leads to an effective mechanism of the interaction between
interlayer Josephson junctions, which can be used to synchronize the junctions. Current-voltage characteristics of chains
of intrinsic junctions are obtained for different values of the parameters.
Zh. éksp. Teor. Fiz. 116, 1798–1816 (November 1999) 相似文献
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在s波超导体/铁磁绝缘层/s波超导体Josephson结(S/FI/S)中,考虑结界面铁磁绝缘层的磁散射和粗糙散射情况下,运用Bogoliubov-de(BdG)方程和Furusaki-Tsukada(FT)的电流公式计算准粒子的输运系数及S/FI/S结的直流Josephson电流与温度T,结两侧的相位差之间的关系,研究表明:结界面的磁散射和粗糙散射均抑制结中准粒子的Andreev反射,降低了流过S/FI/S结的直流Josephson电流。 相似文献
12.
Hideaki Takayanagi R. Inoue T. Akazaki K. Tanaka I. Suemune 《Physica C: Superconductivity and its Applications》2010,470(19):814-817
Superconducting transport is measured between two superconducting electrodes at the n-type semiconductor side of a superconductor-based LED where a Josephson junction is formed. The characteristics of the Josephson junction are found to be modulated by applying voltage to the normal electrode at the p-type semiconductor side. The Josephson junction characteristics show an extraordinary sensitivity to the radiative recombination process, which we estimate as the recombination efficiency. 相似文献
13.
The response of YBaCuO Josephson junctions on a bicrystalline substrate to the action of microwave radiation is found to contain,
besides the Josephson response, a contribution associated with the tunneling of quasiparticles through channels formed by
localized states in the region of the Josephson junction. It is shown that this contribution is associated with an increase
in the conduction through these channels under the action of the radiation on the junction.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 6, 416–420 (25 September 1996) 相似文献
14.
A. M. Bobkov 《JETP Letters》2006,83(3):98-102
The Josephson current between d-wave superconductors is investigated in the framework of the tight-binding lattice model.
The junction is modeled by a small number of connecting bonds. It is found that the Josephson current through one bond vanishes
when at least one of the superconductors has the (110) interface-to-crystal orientation. Interference between the nearest
bonds appears to be very important. In particular, it is the interference term that leads to the nonzero Josephson current
for the (110) orientation. Also, interference of two connecting bonds manifests itself in nonmonotonic behavior of the critical
Josephson current in a dependence on the distance between the bonds.
The text was submitted by the author in English. 相似文献
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《Physics letters. A》2020,384(21):126515
Josephson sandwich is considered, along which the radiating chain of vortices travels. Uniform movement of the chain is supported by bias current. The current-voltage characteristic connecting this current with the voltage at the Josephson junction is found. It is shown that when the current increases, generation of electromagnetic waves with frequency weakly dependent on the current is possible. 相似文献
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M. A. Zelikman 《Technical Physics》2002,47(7):821-828
The pinning energy of plane (laminar) vortices in a 3D Josephson medium is calculated within a continuous vortex model considering
functions of two types: V=1−cosϕ and V= 2/π4ϕ2(2π−ϕ)2. The shape and energy of the stable and unstable vortices are found with an algorithm for the exact numerical solution of
a set of difference equations. The vortex magnetic and Josephson energies diverge. The magnetic and Josephson components of
the pinning energy are close in magnitude but differ in sign; as a result, the total pinning energy is smaller than its components
by one order of magnitude. This result is confirmed analytically. An analytical computing method within the continuous vortex
model is suggested. This method preserves the difference terms in the energy expression. The magnetic energy found by this
method differs from the Josephson energy in magnitude, and the magnetic component of the pinning energy is opposite in sign
to the Josephson component. Comparative analysis of the approximate approaches to energy calculation within the continuous
vortex model when the difference terms are retained and when they are replaced by derivatives is performed. It is shown that
the continuous vortex model gives incorrect values of the Josephson and magnetic components of the pinning energy. The actual
values are several tens or several hundreds of times higher than those obtained with the continuous vortex model. Yet, since
the Josephson and magnetic components of the pinning energy have different signs, the exact value of the total pinning energy
and the approximate value obtained within the continuous vortex model differ insignificantly. 相似文献
17.
Gonnelli RS Calzolari A Daghero D Ummarino GA Stepanov VA Giunchi G Ceresara S Ripamonti G 《Physical review letters》2001,87(9):097001
We present the first observation of the dc and ac Josephson effect in MgB(2) break junctions. The junctions, obtained at 4.2 K in high-quality, high-density polycrystalline metallic MgB(2) samples, show a nonhysteretic dc Josephson effect. By irradiating the junctions with microwaves we observe clear Shapiro steps spaced by the ideal Delta V value. The temperature dependence of the dc Josephson current and the dependence of the height of the steps on the microwave power are obtained. These results directly prove the existence of pairs with charge 2e in MgB(2) and give evidence of the superconductor-normal metal-superconductor weak link character of these junctions. 相似文献
18.
We study the stationary Josephson effect for neutral fermions across the BCS-BEC (Bose-Einstein condensate) crossover, by solving numerically the Bogoliubov-de Gennes equations at zero temperature. The Josephson current is found to be considerably enhanced for all barriers at about unitarity. For vanishing barrier, the Josephson critical current approaches the Landau limiting value which, depending on the coupling, is determined by either pair-breaking or sound-mode excitations. In the coupling range from the BCS limit to unitarity, a procedure is proposed to extract the pairing gap from the Landau limiting current. 相似文献
19.
We investigate the Josephson effect between two coupled superconductors, coupled by the tunneling of pairs of electrons, in the regime that their energy level spacing is comparable to the bulk superconducting gap, but neglecting any charging effects. In this regime, BCS theory is not valid, and the notion of a superconducting order parameter with a well-defined phase is inapplicable. Using the density matrix renormalization group, we calculate the ground state of the two coupled superconductors and extract the Josephson energy. The Josephson energy is found to display a reentrant behavior (decrease followed by increase) as a function of increasing level spacing. For weak Josephson coupling, a tight-binding approximation is introduced, which illustrates the physical mechanism underlying this reentrance in a transparent way. The DMRG method is also applied to two strongly coupled superconductors and allows a detailed examination of the limits of validity of the tight-binding model.Received: 8 September 2003, Published online: 28 May 2004PACS:
74.20.-z Theories and models of superconducting state - 74.78.-w Superconducting films and low-dimensional structures - 74.50. + r Tunneling phenomena; point contacts, weak links, Josephson effects 相似文献
20.
LI Xiao-Wei 《理论物理通讯》2009,52(4):721-725
The Bogoliubov de Gennes equation is applied to the study ofcoherence effects in the ferromagnetic superconductor/insulator/normalmetal/insulator/ferromagnetic/superconductor (FS/I/N/I/FS) junction. We calculated the Josephson current in FS/I/N/I/FS as a function of exchange field in ferromagnetic superconductor, temperature, and normal metal thickness. It is found that the Josephson critical current in FS/I/N/I/FS exhibits oscillations as a function of the length of normal metal. The exchange field always suppresses the Josephson critical current Ip for a parallel configuration of the magnetic moments of two ferromagnetic superconductor (FS) electrodes. In the antiparallel configuration, the Josephson critical current IAp at the minimum values of oscillation increases with the exchange field for strong barrier strength and at low temperatures. 相似文献