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1.
The Josephson effects in the ferromagnetic superconductor junctions of the equal spin pairing symmetry are investigated by a Furusaki–Tsukada-like formula. It is shown that the internal phase difference between the two different anisotropic superconductors plays an important role on the Josephson current. The current is predicted to be an oscillation function of the macroscopic phase difference with the period 2π, π, or π/2 depending on the different orbital pairing symmetries of the superconductors of the junction. 相似文献
2.
Josephson current versus potential strength of the interface in ferromagnetic superconductors
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Hamidreza Emamipour 《中国物理 B》2014,(5):541-545
Based on the scattering theory, we calculate the Josephson current in a junction between two ferromagnetic superconductors as a function of the interface potential z. We consider the ferromagnetic superconductor(FS) in three different Cooper pairing states: spin singlet s-wave pairing(SWP) state, spin triplet opposite spin pairing(OSP) state, and spin triplet equal spin pairing(ESP) state. We find that the critical Josephson current as a function of z shows clear differences among the SWP, OSP, and ESP states. The obtained results can be used as a useful tool for determining the pair symmetry of the ferromagnetic superconductors. 相似文献
3.
Current-voltage characteristics of tunnel junctions between superconductors with anisotropic pairing
Charge transfer in tunnel junctions between superconductors with anisotropic singlet pairing is considered theoretically on
the basis of the Eilenberger equations for the quasiclassical Green’s functions. New singularities of the current-voltage
characteristics, which are characteristic of the case of anisotropic pairing, are treated analytically assuming that the electrons
reflect specularly from the boundaries of the tunnel barrier. All four contributions to the tunneling current are investigated.
Two of them describe Josephson tunneling, and the other two contributions correspond to the quasiparticle current (the last
term appears only for a variable voltage). Different dependences of the order parameter on the momentum directions in the
interior of the superconductors and different orientations of the crystal axes relative to the junction plane are considered.
The results of numerical calculations of the current-voltage characteristics for several particular cases are presented.
Zh. éksp. Teor. Fiz. 111, 1120–1146 (March 1997) 相似文献
4.
We report a theoretical study on spin transport in the hybrid Josephson junction composed of singlet s-wave and triplet p-wave superconductor. The node of the triplet pair potential is considered perpendicular to the interface of the junction. Based on a symmetry analysis, we predict that there is no net spin density at the interface of the junction but instead a transverse mode-resolved spin density can exist and a nonzero spin current can flow transversely along the interface of the junction. The predictions are numerically demonstrated by means of the lattice Matsubara Green's function method. It is also shown that, when a normal metal is sandwiched in between two superconductors, both spin current and transverse mode-resolved spin density are only residing at two interfaces due to the smearing effect of the multimode transport. Our findings are useful for identifying the pairing symmetry of the p-wave superconductor and generating spin current. 相似文献
5.
W. Hanke O. Schmitt H. Endres R. Kleiner P. Müller 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(3):465-471
A quantitative analysis of a microscopic model for the intrinsic Josephson effect in high-temperature superconductors based
on interlayer tunneling is presented both within a mean-field BCS evaluation and a numerically essentially exact Quantum Monte-Carlo
study. The pairing correlations in the CuO2-planes are modelled by a 2D Hubbard model with attractive interaction, a model which accounts well for some of the observed
features such as the short planar coherence length. The stack of Hubbard planes is arranged on a torus, which is threaded
by a magnetic flux. The current perpendicular to the planes is calculated as a function of applied flux (i.e. the phase), and - after careful elimination of finite-size effects due to single-particle tunneling - found to display a
sinusoidal field dependence in accordance with interlayer Josephson tunneling. Studies of the temperature dependence of the
supercurrent reveal at best a mild elevation of the Josephson transition temperature compared to the planar Kosterlitz-Thouless
temperature. These and other results on the dependence of the model parameters are compared with a standard BCS evaluation.
Received: 24 February 1998 / Revised: 28 April 1998 / Accepted: 23 June 1998 相似文献
6.
A weak link of two superconductors with s-type pairing through a ferromagnet has been theoretically investigated in the regime of a nonequilibrium spin-dependent distribution
of electrons over energy levels in a ferromagnetic interlayer. It has been shown that, under the given conditions, the triplet
component of the supercurrent-carrying density of states, which does not participate in the Josephson current transfer under
equilibrium and spin-independent nonequilibrium conditions, is involved in the Josephson current transfer through the junction.
In this case, the standard supercurrent transferred by the singlet component of the supercurrent-carrying density of states
remains unchanged as compared to the case of the equilibrium distribution of electrons in the interlayer. An additional current
transferred by the triplet component is controlled by a voltage that controls the specific shape and the degree of nonequilibrium
of the electron distribution function in the interlayer. Depending on this controlling parameter, the additional current can
substantially amplify or attenuate the standard supercurrent and also switch the junction between 0 and π states. 相似文献
7.
8.
《Physica C: Superconductivity and its Applications》1999,311(1-2):93-97
The Josephson coupling between two identical high-temperature superconductors was studied theoretically based on a superconducting–normal (SN) bilayer model with s+id-wave pairing in the S layer. It is indicated that due to the proximity effect between S and N layers as the interlayer hopping t⊥ decreases, the product of the tunneling current through the junction and the normal-state resistance of the junction can be substantially reduced from the value described by the Ambegaokar–Baratoff (AB) theory. Our theoretical result is in good agreement with the experiments. 相似文献
9.
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
10.
We study Josephson junctions between superconductors connected through the helical edge states of a two-dimensional topological insulator in the presence of a magnetic barrier. As the equilibrium Andreev bound states of the junction are 4π periodic in the superconducting phase difference, it was speculated that, at finite dc bias voltage, the junction exhibits a fractional Josephson effect with half the Josephson frequency. Using the scattering matrix formalism, we show that his effect is absent in the average current. However, clear signatures can be seen in the finite-frequency current noise. Furthermore, we discuss other manifestations of the Majorana bound states forming at the edges of the superconductors. 相似文献
11.
The Josephson junction containing localized magnetic moments in a dielectric layer between two superconductors is considered. Conditions are studied under which the phase difference between superconductors in the state with energy minimum is equal to π (such a junction we call π-junction). In addition we consider “one-dimensional” Josephson junction one part (2) of which is π-junction, the other (1) being the usual Josephson junction ( 0 - junction). Conditions are found under which in such a system there is a spontaneous vortex with the centre at the boundary between the parts 1 and 2 and magnetic flux associated with this vortex. The vortex appears by second order phase transition as temperature decreases for Tc. 相似文献
12.
x2-y2
wave superconductors, which form a contact at a tilt angle. The contact is a weak link or a Josephson junction, with properties
determined by the misalignment angle. Complementing existing theories that discuss the influence of dx2-y2 symmetry on the charge transfer across junctions, the ideas presented provide insights into the origin of the junction formed
in such configurations. The mechanism discussed is of relevance for the understanding of the electronic properties of grain
boundaries in superconductors, including the angular dependence of the critical current density.
Received: 5 July 1996/Accepted: 7 January 1997 相似文献
13.
14.
Coherent electron transport in structures with multiband superconductors described by models of intraorbital (the s
± model) and interorbital superconducting pairing has been theoretically considered. Conductivities of junctions of a single-band
normal metal with superconducting pnictides for these pairing models have been calculated. Temperature and phase dependences
of the Josephson current through junctions containing a conventional Bardeen-Cooper-Schrieffer superconductor and a superconducting
pnictide have been calculated within the considered pairing models taking into account temperature dependences of superconducting
order parameters. 相似文献
15.
16.
由Bogoliubov-de Gennes方程得到铁磁超导共存态(FS)的自洽方程,利用推广的Furusaki-Tsukada的电流公式计算了铁磁超导态/绝缘层/自旋三重态p波超导体(FS/I/p)结的直流Josephson电流随结的温度、相位差以及FS中磁交换能、结界面的势垒散射强度的变化关系.研究表明:FS中磁交换能、结界面的势垒散射均抑制FS/I/p结的直流Josephson电流.当自旋三重态超导体具有px波配对势时,自旋三重态超导体结的直流Josephson电流随结两侧相位差的振荡周期是π.
关键词:
铁磁超导态
自旋三重态超导体
p波超导体
直流Josephson电流 相似文献
17.
I. V. Borisenko K. Y. Constantinian Yu. V. Kislinskii G. A. Ovsyannikov 《Journal of Experimental and Theoretical Physics》2004,99(6):1223-1232
Experimentally observed features of the electrical and noise characteristics of bicrystal junctions of cuprate superconductors, such as linearity of the critical current density versus square root of the junction transparency and increase in the spectral density of shot noise for small bias voltages (below the superconducting gap), indicate that the superconducting current in cuprate bicrystal junctions is determined by the passage of quasi-particles through a potential barrier at the superconductor boundaries. This process involves bound states appearing as a result of multiple Andreev reflections in superconductors with dominant wavefunction components of the d x 2 ? y 2 symmetry type. At the same time, interpretation of the experimental current-phase and current-magnetic field curves requires that the character of faceting at the bicrystal junctions would be also taken into account. 相似文献
18.
A relation is established between the transport current flowing through the entire S 1 IS 2 WS 3 layered structure and the velocity of a fast vortex. The fast vortex exists when the Swihart velocity in the waveguide is significantly higher than that in the Josephson junction. It is demonstrated that the main contribution to the Lorentz force that induces the vortex motion is due to the current flowing through the waveguide and skin layers of the adjacent superconductors.
相似文献19.
M. Yu. Kupriyanov N. G. Pugach M. M. Khapaev A. V. Vedyayev E. B. Goldobin D. Koelle R. Kleiner 《JETP Letters》2008,88(1):45-48
Within the framework of the Usadel equations, the Josephson effect in a superconductor-insulator-ferromagnet-superconductor
(SIFS) structure with a spatially heterogeneous transparency of the SF interface has been studied. It is shown that, at a
certain thickness of the F layer, a stepwise variation of the transparency leads to the formation of a region of size ∼ξ
F
(coherence length in a ferromagnet), where the Josephson supercurrents of different signs may flow. This may lead to the
dependence of the junction critical current on the external magnetic field qualitatively different from the Fraunhofer pattern
typically observed in usual Josephson junctions.
The text was submitted by the authors in English. 相似文献
20.
We study the temperature T and the phase of the Josephson critical current I( φ ) by taking into account the roughness scattering effect at inerface in an f-wave superconductor (S)/Insulator layer (I)/f-wave superconductor (S) junction. It is found that the Josephson critical currents in f-wave S/f-wave S, the barrier strength and the roughness strength at inerface always suppress the Andreev reflection. When α =β, the phase dependence of theJosephson current I ( φ ) between two f-wave S is predicted to be sin φ; particularly, when α ≠β, the phase dependence of the Josephson current I( φ ) between two f-wave superconductors is not predicted to be sin φ and with the barrier strength increasing, the period of the I( φ ) turns decrease. 相似文献