Josephson Effect in d-Wave Superconductor Junctions in a Lattice Model

Shirai, Shota; Tsuchiura, Hiroki; Asano, Yasuhiro; Tanaka, Yukio; Inoue, Jun–ichiro; Tanuma, Y.; Kashiwaya, Satoshi

doi:10.1143/jpsj.72.2299

Cited by 13 publications

(25 citation statements)

References 114 publications

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“…3,4,5,6,7,8,9,10 The ZES is also responsible for the low-temperature anomaly of the Josephson current between the two unconventional superconductors. 11,12,13,14,15,16,17,18,19,20,21 An electron incident into a normal-metal / superconductor (NS) interface suffers the Andreev reflection 22 by the pair potential in the superconductor. As a result, a hole traces back the original propagation path of the incident electron.…”

Section: Introductionmentioning

confidence: 99%

Split of zero-bias conductance peak in normal-metal/d-wave superconductor junctions

2004

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Effects of impurity scatterings on the conductance in normal-metal / d wave superconductor junctions are discussed by using the single-site approximation. So far, the split of the zero-bias conductance peak has been believed to be an evidence of the broken time reversal symmetry states at the surface of high-Tc superconductors. In this paper, however, it is shown that the impurity scattering near the interface also causes the split of the zero-bias conductance peak. Typical conductance spectra observed in experiments at finite temperatures and under external magnetic fields are explained well by the present theory.

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Section: Introductionmentioning

confidence: 99%

Split of zero-bias conductance peak in normal-metal/d-wave superconductor junctions

2004

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“…29 For a square lattice with d x 2 −y 2 -wave superconductor junctions treated within the TB-BdG formalism, ZESs were reported for several interfaces including the {110} interface. 32 However, it was also found that when using a lattice model the appearance of a ZES is sensitive to Friedel oscillations in the wave function. These can cause destructive interference between different surface lattice sites, leading to the disappearance of the ZES.…”

Section: E Ldos and The Existence Of Zesmentioning

confidence: 99%

Effect of nearest neighbor spin-singlet correlations in conventional graphene SNS Josephson junctions

Black‐Schaffer¹,

Doniach²

2009

Phys. Rev. B

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Using the self-consistent tight-binding Bogoliubov-de Gennes formalism we have studied the effect of nearest neighbor spin-singlet bond ͑SB͒ correlations on Josephson coupling and proximity effect in graphene SNS Josephson junctions with conventional s-wave superconducting contacts. For strong enough coupling the SB correlations give rise to a superconducting state with either an extended s-, d x 2 −y 2-, or d xy -wave symmetry, or different combinations of the d-waves with the d x 2 −y 2 + id xy -state favored in the bulk. Despite the s-wave superconducting state in the contacts, the SB pairing state inside the junction has d-wave symmetry and clean, sharp interface junctions resemble a "bulk-meets-bulk" situation with very little interaction between the two different superconducting states. In fact, due to a finite-size suppression of the superconducting state, a stronger SB coupling constant than in the bulk is needed in order to achieve SB pairing in a junction. For both short clean zigzag and armchair junctions the d-wave state that has a zero Josephson coupling to the s-wave state is chosen and therefore the Josephson current decreases when a SB pairing state develops in these junctions. In more realistic junctions, with smoother doping profiles and atomic scale disorder at the interfaces, it is possible to achieve some coupling between the contact s-wave state and the SB d-wave states. In addition, by breaking the appropriate lattice symmetry at the interface in order to induce the other d-wave state, a nonzero Josephson coupling can be achieved which leads to a substantial increase in the Josephson current. We also report on the LDOS of the junctions and on a lack of zero energy states at interfaces despite the unconventional order parameters, which we attribute to the near degeneracy of the two d-wave solutions and their mixing at a general interface.

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“…20,21,22,23,24 So far a considerable number of studies have been made on the ZES itself and related phenomena of transport properties in both spin-singlet and spin-triplet unconventional superconductor junctions. 7,8,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50 The conductance in normal-metal / superconductor (NS) junctions is calculated from the normal and the Andreev reflection 51 coefficients which are obtained by solving the Bogoliubov-de Gennes (BdG) equation 52 under appropriate boundary conditions at the junction interface. Consequently we easily find the zero-bias conductance peak (ZBCP) in NS junctions of high-T c superconductors.…”

Section: Introductionmentioning

confidence: 99%

Phenomenological theory of zero-energy Andreev resonant states

2004

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A conceptual consideration is given to a zero-energy state (ZES) at the surface of unconventional superconductors. The reflection coefficients in normal-metal / superconductor (NS) junctions are calculated based on a phenomenological description of the reflection processes of a quasiparticle. The phenomenological theory reveals the importance of the sign change in the pair potential for the formation of the ZES. The ZES is observed as the zero-bias conductance peak (ZBCP) in the differential conductance of NS junctions. The split of the ZBCP due to broken time-reversal symmetry states is naturally understood in the present theory. We also discuss effects of external magnetic fields on the ZBCP.

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Josephson Effect in d-Wave Superconductor Junctions in a Lattice Model

Cited by 13 publications

References 114 publications

Split of zero-bias conductance peak in normal-metal/d-wave superconductor junctions

Split of zero-bias conductance peak in normal-metal/d-wave superconductor junctions

Effect of nearest neighbor spin-singlet correlations in conventional graphene SNS Josephson junctions

Phenomenological theory of zero-energy Andreev resonant states

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