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本文用隧道哈密顿研究了具有粒子数反转机制超导体的Josephson效应。结果指出,正常电流部分在不加外电压时消失,而反常电流部分则不仅依赖于结两侧的位相差,且与Fermi准能级μ有关,在外电压为零时以4μ的频率随时间振荡。 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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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
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通过计算具有铁磁绝缘层的双层f波超导体结中铁磁绝缘层的磁散射对直流Josephson电流的影响,研究了f波超导体(fS)/铁磁绝缘层(FI)/f波超导体(fS)结的直流Josephson电流与温度和结两侧相位差((?))之间的关系.研究表明:fS/FI/fS结界面的粗糙散射和磁散射总是抑制结中准粒子的Andreev反射,降低流过fS/FI/fS结的直流Josephson电流,且结的直流Josephson电流随相位差的变化曲线强烈依赖于f波超导体的晶轴方位角(α). 相似文献
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在超导体铁磁体绝缘层超导体结(SFIS)中,运用BogoliubovdeGennes(BdG)方程和FurusakiTsukada(FT)电流公式,计算铁磁超导共存态的自洽方程和SFIS结中的直流Josephson电流.研究表明,铁磁超导态的磁交换能h对准粒子的Andreev反射有抑制作用,使得SFIS结中的直流Josephson电流随铁磁超导共存态的磁交换能h增大而减弱
关键词:
S/F-I-S结
铁磁超导态
直流Josephson电流 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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全电流超导隧道结电子模拟器 总被引:1,自引:0,他引:1
本文描述的电子模拟器完整地模拟了超导隧道结中的各项隧道电流,它包含了频率、温度和超导能隙的影响,并考虑了非线性准粒子电阻和电抗项的作用.论文简述了电子模拟器的基本原理、电路,给出了恒压源与恒流源两种偏置条件下的直流与交流 I-V 特性,还得到了上述两种偏置条件下的约瑟夫逊台阶及光子辅助的准粒子隧道效应台阶等高频行为. 相似文献
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K. V. Kalashnikov A. A. Artanov L. V. Filippenko V. P. Koshelets 《Physics of the Solid State》2016,58(11):2191-2195
The regimes of operation of a superconductor–insulator–superconductor tunnel junction based on three-layer structures Nb/AlOx/Nb and Nb/AlN/NbN as a harmonic mixer (for frequencies of the order of 600 and 20 GHz, respectively) and a frequency up-converter (in the frequency range from 0.1 to 5.0 GHz) have been investigated experimentally. The quasiparticle and Josephson mixing regimes have been compared. It has been shown that, in some practical applications, such as the use of the superconductor–insulator–superconductor junction as a cryogenic harmonic phase detector, the Josephson mixing regime is more preferable, because it can provide a higher signal and a greater signal-to-noise ratio as compared to the quasiparticle mixing regime. It has also been demonstrated that the Josephson mixing regime is promising for the use in signal multiplexing systems for superconducting detectors. 相似文献
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In the quasi-two-dimensional (Q2D) electron gas of an InAs channel between an AlSb substrate and superconducting niobium layers, the proximity effect induces a pair potential so that a Q2D mesoscopic superconducting/normal/superconducting (SNS) junction forms in the channel. The pair potential is calculated with quasiclassical Green’s functions in the clean limit. For such a junction, alternating Josephson currents and current–voltage characteristics (CVCs) are computed, using the nonequilibrium quasiparticle wavefunctions which solve the time-dependent Bogoliubov–de Gennes equations. The CVCs exhibit features found experimentally by the Kroemer group: a steep rise of the current at small voltages (‘foot’) changes at a ‘corner current’ to a much slower increase of current with higher voltages, and the zero-bias differential resistance increases with temperature. Phase-coherent multiple Andreev reflections and the associated Cooper pair transfers are the physical mechanisms responsible for the oscillating Josephson currents and the CVCs. Additional experimental findings not reproduced by the theory require model improvements, especially a consideration of the external current leads which should give rise to hybrid quasiparticle/collective-mode excitations. 相似文献
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Using tunneling spectroscopy, we have measured the local electron energy distribution function in the normal part of a superconductor-normal metal-superconductor (SNS) Josephson junction containing an extra lead to a normal reservoir. In the presence of simultaneous supercurrent and injected quasiparticle current, the distribution function exhibits a sharp feature at very low energy. The feature is odd in energy and odd under reversal of either the supercurrent or the quasiparticle current direction. The feature represents an effective temperature gradient across the SNS Josephson junction that is controllable by the supercurrent. 相似文献
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L. J. Geerligs S. M. Verbrugh P. Hadley J. E. Mooij H. Pothier P. Lafarge C. Urbina D. Estève M. H. Devoret 《Zeitschrift für Physik B Condensed Matter》1991,85(3):349-355
We have operated a Cooper pair pump, a linear array of superconducting tunnel junctions in which single Cooper pairs are moved under the influence of ac signals applied to two gate electrodes. The pump is based on the Coulomb blockade of charge tunneling. Because of the small junction capacitance precisely one Cooper pair is transferred per ac cycle. The current-voltage characteristics of this device show current plateaus close to 2ef, wheref is the frequency of the ac voltages. Deviations are explained in terms of Zener tunneling, Cooper pair co-tunneling, and sporadic quasiparticle tunneling. 相似文献
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We propose a quasiparticle interferometer for experimentally confirming the predicted phase interaction between a quasiparticle and a superconducting state at the superconductor- normal-metal (S-N) interface. The phase interaction is caused by Andreev reflection. The proposed interferometer consists of a Josephson junction and a Y-junction composed of normal electron waveguides. In the setup, the phase interaction due to Andreev reflection affects the resistance across the end of a waveguide and an electrode of the Josephson junction. Thus the amount of supercurrent flowing through the Josephson junction can control the resistance. 相似文献
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A two-dimensional voltage image of the energy gap distribution of a superconducting tunnel junction was obtained by scanning the current biased junction with an electron beam and detecting the voltage change δV. The value of the energy gap at the point of irradiation was determined quantitatively from the δV σ(V) curves, where σ(V) is the electric conductance of the junction. Further the quasiparticle diffusion length was found by measuring the length of the transition between a high- and low-gap region generated by a double tunnel junction configuration. The theoretical predictions could be verified by investigating a double tunnel junction configuration, where the energy gap could be changed deliberately by quasiparticle injection. 相似文献
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V. A. Andrianov V. P. Gor’kov 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(6):747-751
A mathematical model of a strip X-ray detector has been developed. The detector consists of a long superconducting strip with two tunnel junctions at both ends. The model developed takes into account the diffusion of nonequilibrium quasiparticles, their capture to the region of the tunnel junctions, and quasiparticle losses in the bulk and at the boundaries of the superconducting strip. Analytical solutions have been obtained for the boundary conditions of the third kind. It is shown that the quasiparticle losses at the strip boundaries lead to a dependence of the detector signal amplitude on the transverse coordinate of the photon absorption point and deteriorate the energy and spatial resolution. The spectral line has been calculated with allowance for the contribution of electronic noise. 相似文献
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Influence of Rashba spin-orbit coupling on Josephson effect in triplet superconductor/two-dimensional semiconductor/triplet superconductor junctions 下载免费PDF全文
Bin-Hao Du 《中国物理 B》2022,31(7):77201-077201
We study theoretically Josephson effect in a planar ballistic junction between two triplet superconductors with p-wave orbital symmetries and separated by a two-dimensional (2D) semiconductor channel with strong Rashba spin-orbit coupling. In triplet superconductors, three types of orbital symmetries are considered. We use Bogoliubov-de Gennes formalism to describe quasiparticle propagations through the junction and the supercurrents are calculated in terms of Andreev reflection coefficients. The features of the variation of the supercurrents with the change of the strength of Rashba spin-orbit coupling are investigated in some detail. It is found that for the three types of orbital symmetries considered, both the magnitudes of supercurrent and the current-phase relations can be manipulated effectively by tuning the strength of Rashba spin-orbit coupling. The interplay of Rashba spin-orbit coupling and Zeeman magnetic field on supercurrent is also investigated in some detail. 相似文献
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We study electronic transport through an n-p junction in graphene irradiated by an electromagnetic field (EF). In the absence of EF one may expect the perfect transmission of quasiparticles flowing perpendicular to the junction. We show that the resonant interaction of propagating quasiparticles with the EF induces a dynamic gap between electron and hole bands in the quasiparticle spectrum of graphene. In this case the strongly suppressed quasiparticle transmission is only possible due to interband tunneling. The effect may be used to control transport properties of diverse structures in graphene, e.g., n-p-n transistors and quantum dots, by variation of the intensity and frequency of the external radiation. 相似文献