共查询到20条相似文献,搜索用时 15 毫秒
1.
T. E. Golikova F. Hübler D. Beckmann N. V. Klenov S. V. Bakurskiy M. Yu. Kupriyanov I. E. Batov V. V. Ryazanov 《JETP Letters》2013,96(10):668-673
Specific features of the proximity effect and Josephson behavior of submicron planar SNS junctions fabricated by electron beam lithography and shadow evaporation have been studied experimentally and theoretically. The critical current of the junctions has been found to drastically increase with a decrease in temperature, which is associated with a change in the effective size of the weak link owing to the additional SN interface. 相似文献
2.
A response of the Josephson SNS junction to a heat flow and to an electric current has been studied with the same junction. A non-monotonous dependence of a critical heat flow on the magnetic field Be is discovered. This dependence is found to be completely identical with the measured function Ic(Be). 相似文献
3.
We predict a novel type of Josephson effect to occur in triplet-superconductor-ferromagnet-triplet-superconductor Josephson junctions. We show that the Josephson current, IJ, exhibits a rich dependence on the relative orientation between the ferromagnetic moment and the d vectors of the superconductors. This dependence can be used to build several types of Josephson current switches. Moreover, we predict an unconventional sign change of IJ with increasing temperature. 相似文献
4.
The Josephson effect in p-wave superconductor/diffusive normal metal/p-wave superconductor junctions is studied theoretically. Amplitudes of Josephson currents are several orders of magnitude larger than those in s-wave junctions. Current-phase (J-phi) relations in low temperatures are close to those in ballistic junctions such as J proportional to sin(phi/2) and J proportional to phi even in the presence of random impurity potentials. A cooperative effect between the midgap Andreev resonant states and the proximity effect causes such anomalous properties and is a character of the spin-triplet superconductor junctions. 相似文献
5.
M. Siegel E. Heinz P. Seidel V. Hilarius 《Zeitschrift für Physik B Condensed Matter》1991,83(3):323-326
We have investigated dc and ac Josephson effects on YBa2Cu3O7–x ceramic samples using the break junction technique. The critical current was measured as a function of external magnetic field and temperature. The field dependence shows superposition effects of junction and SQUID behavior. The critical current depends linearly on temperature like for SNS junctions. We observed Shapiro steps with microwave radiation with a frequency of 35 GHz at 4.2 K and 77 K, respectively. Deviations of the step height from Bessel behavior at low microwave power are explained within the Stewart-McCumber model using small capacitances of the junction in simulation calculations. 相似文献
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7.
For certain orientations of Josephson junctions between two px-wave or two d-wave superconductors, the subgap Andreev bound states produce a
-periodic relation between the Josephson current I and the phase difference
:
. Consequently, the ac Josephson current has the fractional frequency
, where V is the dc voltage. In the tunneling limit, the Josephson current is proportional to the first power (not square) of the electron tunneling amplitude. Thus, the Josephson current between unconventional superconductors is carried by single electrons, rather than by Cooper pairs. The fractional ac Josephson effect can be observed experimentally by measuring frequency spectrum of microwave radiation from the junction. We also study junctions between singlet s-wave and triplet px-wave, as well as between chiral
-wave superconductors.Received: 24 September 2003, Published online: 2 April 2004PACS:
74.50. + r Tunneling phenomena; point contacts, weak links, Josephson effects - 74.70.Kn Organic superconductors - 74.72.-h Cuprate superconductors (high-Tc and insulating parent compounds) - 74.70.Pq Ruthenates 相似文献
8.
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
9.
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
10.
A detailed analysis of the control space characterization of phase locked states and chaotic attractors in Josephson junctions
is presented, based on a model that includes both quadratic damping and cosine interference terms. In addition, some novel
features of the nonlinear characteristics of the junction like evolution of basin boundaries, bifurcation structure analysis
and scaling behaviour of Lyapunov exponent are discussed. 相似文献
11.
S. Madsen N.F. Pedersen P.L. Christiansen 《Physica C: Superconductivity and its Applications》2010,470(19):822-826
Long Josephson junctions have for some time been considered as a source of THz radiation. We consider here a stack of Josephson junctions as a model for the anisotropic high temperature superconductors in particular those of the BSCCO family. Solitons (fluxons) moving coherently in such junctions is a possible source for radiation. Analytical computations of the bunched state as well as bunching inducing methods are discussed. A new model for the interpretation of THz radiation experiments is suggested. 相似文献
12.
We construct a gravitational dual of a Josephson junction. Calculations on the gravity side reproduce the standard relation between the current across the junction and the phase difference of the condensate. We also study the dependence of the maximum current on the temperature and size of the junction and reproduce familiar results. 相似文献
13.
The magnetic field dependences of critical current are numerically constructed for a long Josephson junction with a shunt-or resistor-type microscopic inhomogeneities and compared to the critical curve of a junction with exponentially varying width. The numerical results show that it is adequate to replace the distributed inhomogeneity of a long Josephson junction by an inhomogeneity localized at one of its ends, which has certain technological advantages. It is also shown that the critical curves of junctions with exponentially varying width and inhomogeneities localized at the ends are unaffected by the mixed fluxon-antifluxon distributions of the magnetic flow. This fact may explain the improvement of the spectra of microwave radiation noted in the literature. 相似文献
14.
Yunxiao Zhang 《中国物理 B》2022,31(10):107402-107402
Recently, a Corbino-geometry type of Josephson junction constructed on the surface of topological insulators has been proposed for hosting and braiding Majorana zero modes. As a first step to test this proposal, we successfully fabricated Corbino-geometry Josephson junctions (JJs) on the surface of Bi2Te3 flakes. Ac Josephson effect with fractional Shapiro steps was observed in the Corbino-geometry JJs while the flux in the junction area was quantized. By analyzing the experimental data using the resistively shunted Josephson junction model, we found that the Corbino-geometry JJs exhibit a skewed current—phase relation due to its high transparency. The results suggest that Corbino-geometry JJs constructed on the surface of topological insulators may provide a promising platform for studying Majorana-related physics. 相似文献
15.
Y.C. Tao 《Physica B: Condensed Matter》2008,403(1):95-102
Using a general expression for dc Josephson current, we study the Josephson effect in ballistic superconductor (SC)/ferromagnetic semiconductor (FS)/SC junctions, in which the mismatches of the effective mass and Fermi velocity between the FS and SC, spin polarization P in the FS, as well as strengths of potential scattering Z at the interfaces are included. It is shown that in the coherent regime, the oscillatory dependences of the maximum Josephson current on the FS layer thickness L and Josephson current on the macroscopic phase difference φ for the heavy and light holes, resulting from the spin splitting energy gained or lost by a quasiparticle Andreev-reflected at the FS/SC interface, are much different due to the different mismatches in the effective mass and Fermi velocity between the FS and the SC, which is related to the crossovers between positive (0) and negative (π) couplings or equivalently 0 and π junctions. Also, we find that, for the same reason, Z and P are required not to surpass different critical values for the Josephson currents of the heavy and light holes. Furthermore, it is found that, for the dependence of the Josephson current on φ, regardless of how L,Z, and P change, the Josephson junctions do not transit between 0 and π junctions for the light hole. 相似文献
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17.
We report on a nontrivial type of slow-fast dynamics in a Josephson junction model externally shunted by a resistor and an inductor. For large values of the shunt inductance the slow manifold is highly folded, and different types of dynamical behavior in the fast variable are possible in dependence on the other parameters of the junction. We discuss how particular features of the dynamics are manifested in the current-voltage characteristics of the shunted junction.Received: 10 March 2003, Published online: 11 August 2003PACS:
05.45.-a Nonlinear dynamics and nonlinear dynamical systems -
85.25.Cp Josephson devices -
74.81.-g Inhomogeneous superconductors and superconducting systems 相似文献
18.
《Solid State Communications》1987,63(9):853-855
The observations of the ac Josephson effect in Y-Ba-Cu-O superconducting weak link were reported. The Y-Ba-Cu-O sample had a Tc=90 K. The I–V characteristics of the weak link junction were mearsured at 77 K. The junction had a Ic=0.43 mA and the normal resistance Rn=0.38 ohm. 10.15 GHz microwave was applied to the junction and the rf-induced steps up to n=10 were observed. The dependence of the step height on the rf level was in agreement with ordinary Josephson tunneling behavior. 相似文献
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20.
Superconducting loop with two Josephson SNS junction was investigated. The junctions were biased by a heat flow. A voltage across the junctions was observed when the heat flow exceeded the critical value. This critical heat flow was a periodical function of magnetic flux in the loop. The period and the magnitude of modulation of this curve coincide with the parameters of the dependence of critical current through the same sample upon the magnetic flux in the absence of the heat flow. 相似文献