Quasiclassical theory of spontaneous currents at surfaces and interfaces of d-wave superconductors

Amin, M. H. S.; Omelyanchouk, A. N.; Rashkeev, Sergey N.; Coury, Michael; Zagoskin, A. M.

doi:10.1016/s0921-4526(01)01561-7

Cited by 36 publications

(59 citation statements)

References 51 publications

(56 reference statements)

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“…[6] to suggest an s g + -wave model of the order parameter to describe the superconductivity in the borocarbides: J j is an alternating-sign quantity, which means that some reflected trajectories experience the intrinsic phase difference. This result in the suppression of the order parameter in the vicinity of the interface between two superconductors similar to what is known about the contact of two d-wave superconductors (see [7] and references therein); and in this case the non-self-consistent calculation, presented below, can be justified for the weak links in the form of both the point contact and the plane boundary between two banks. Another consequence of the intrinsic phase difference is the appearance of the spontaneous phase difference (which means that at equilibrium, when j J = 0 and dj /d J f > 0, the phase difference is not zero: f f = ¹ 0 0) and the spontaneous interface current at equilibrium at f f = 0 (which is demonstrated below).…”

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confidence: 65%

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Josephson effect in a weak link between borocarbides

Kolesnichenko

Shevchenko

2005

Low Temperature Physics

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A stationary Josephson effect is analyzed theoretically for a weak link between borocarbide superconductors. It is shown that different models of the order parameter result in qualitatively different current-phase relations. PACS: 74.50.+rDetermination of the symmetry of the order parameter D in novel unconventional superconductors is important for the development of modern physics of superconductivity because the dependence of D( ) k on the direction of the electron wave vector k on the Fermi surface determines all of the kinetic and thermodynamic characteristics of the superconductor. Calculation of the order parameter D( ) k is a fundamental problem and requires knowledge of the pairing potential. Some general information about D( ) k can be obtained from the symmetry of a normal state, i.e., according to the Landau theory of secon-order phase transitions [1], the order parameter transforms only accoding to irreducible representations of the symmetry group of the normal state (for review, see [2]). Nevertheless, symmetry considerations reserve for the order parameter considerable freedom in the selection of irreducible representation and its basis functions. Therefore in many papers authors consider different models of the order parameter, which are based on possible representations of crystallographic point groups. The subsequent comparison of theoretical results with experimental data makes it possible to choose between available models of the order parameter. The Josephson effect in superconducting weak links is one of the most suitable instruments for investigation of the symmetry of D( ) k . It has heen shown, for example, that current-phase relations j J ( ) j in unconventional superconductors are quite different for different models of D( ) k , and hence the study of the Josephson effect enables one to judge the applicability of different models to the novel superconductors [3].Borocarbides, such as YNi 2 B 2 C and LuNi 2 B 2 C, exhibit unconventional superconductivity. There is strong evidence that in these materials the order parameter is highly anisotropic [4]. The order parameter in these compounds has fourfold symmetry, and there are deep minima along the [100] and [010] directions [4,5]. Both the symmetry of the borocarbide crystal structure and the experimental results have allowed the authors of Refs.[6] to suggest an s g + -wave model of the order parameter to describe the superconductivity in the borocarbides: J j is an alternating-sign quantity, which means that some reflected trajectories experience the intrinsic phase difference. This result in the suppression of the order parameter in the vicinity of the interface between two superconductors similar to what is known about the contact of two d-wave superconductors (see [7] and references therein); and in this case the non-self-consistent calculation, presented below, can be justified for the weak links in the form of both the point contact and the plane boundary between two banks. Another consequence of the intrinsic phase difference is th...

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confidence: 65%

“…In what follows we study the stationary Josephson effect in the weak link between two borocarbides, described by the s g + -wave model (1) [7]. The standard procedure of matching the solutions of the bulk Eilenberger equations at the boundary gives the Matsubara Green's function $ ( ) G w 0 at the contact at x = 0 [7].…”

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Josephson effect in a weak link between borocarbides

Kolesnichenko

Shevchenko

2005

Low Temperature Physics

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“…24. We rewrite the Eilenberger equations employing the Riccati parametrization, 25 which is well suited for numerical integration.…”

Section: Self-consistent Numerical Resultsmentioning

confidence: 99%

Density of states ind-wave superconductors of finite size

Fominov

Golubov

2004

Phys. Rev. B

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We consider the effect of the finite size in the ab-plane on the surface density of states (DoS) in clean d -wave superconductors. In the bulk, the DoS is gapless along the nodal directions, while the presence of a surface leads to formation of another type of the low-energy states, the midgap states with zero energy. We demonstrate that finiteness of the superconductor in one of dimensions provides the energy gap for all directions of quasiparticle motion except for θ = 45• (θ is the angle between the trajectory and the surface normal); then the angle-averaged DoS behaves linearly at small energies. This result is valid unless the crystal is 0• -or 45• , where α is the angle between the a-axis and the surface normal). In the special case of α = 0• , the spectrum is gapped for all trajectories θ; the angle-averaged DoS is also gapped. In the special case of α = 45• , the spectrum is gapless for all trajectories θ; the angle-averaged DoS is then large at low energies. In all the cases, the angle-resolved DoS consists of energy bands that are formed similarly to the Kronig-Penney model. The analytical results are confirmed by a self-consistent numerical calculation.

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“…16,19, 23 a polarized dissipation-less supercurrent of spins had been predicted. It was shown that the current-phase dependencies are totally different from the current-phase dependencies of the junction between conventional s-wave superconductors [24] and high temperature d-wave superconductors [25].…”

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Charge and spin currents in a ballistic SNS Josephson junction between p-wave superconductors

Rashedi

Rahnavard

Kolesnichenko

2010

Low Temperature Physics

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Charge and spin transport properties of a clean TS-N-TS Josephson junction (triplet superconductor-normal metal-triplet superconductor) are studied using the quasiclassical Eilenberger equation for Green's function. Effects of thickness of normal layer between superconductors on the spin and charge currents are investigated. The effect of a misorientation between triplet superconductors which creates the spin current is the main subject of this paper. It is shown that for some values of phase difference between superconductors the spin current exists in the absence of charge current and vice versa.

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Quasiclassical theory of spontaneous currents at surfaces and interfaces of d-wave superconductors

Cited by 36 publications

References 51 publications

Josephson effect in a weak link between borocarbides

Josephson effect in a weak link between borocarbides

Density of states ind-wave superconductors of finite size

Charge and spin currents in a ballistic SNS Josephson junction between p-wave superconductors

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