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Testa, Gianluca; Sarnelli, E.; Monaco, A.; Esposito, E.; Ejrnæs, M.; Kang, Dae Joon; Mennema, S. H.; Tarte, E.J.; Blamire, M. G.

doi:10.1103/physrevb.71.134520

Cited by 52 publications

(39 citation statements)

References 31 publications

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“…8, SR formula does not work in ballistic d-wave junctions for ␣ 0 and ␤ 0 where MARS influence severely the charge transport at low temperatures. It was shown both theoretically 9,10 and experimentally 11,12 that MARS induce a nonmonotonic temperature dependence of the maximum Josephson current in DID junctions. On the other hand, SR formula has been extensively used to analyze experiments with various types of HTS Josephson junctions.…”

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Angular dependence of Josephson currents in unconventional superconducting junctions

et al. 2007

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Josephson effect in junctions between unconventional superconductors is studied theoretically within the model describing the effects of interface roughness. The particularly important issue of applicability of the frequently used Sigrist-Rice ͑SR͒ formula for Josephson current in d-wave superconductor/insulator/d-wave superconductor junctions is addressed. We show that although the SR formula is not applicable in the ballistic case, it works well for rough interfaces when the diffusive normal metal regions exist between the d-wave superconductor and the insulator. It is shown that the SR approach only takes into account the component of the d-wave pair potential symmetric with respect to an inversion around the plane perpendicular to the interface. Similar formula can be derived for general unconventional superconductors with arbitrary angular momentum l. [1][2][3][4] Because of such unconventional symmetry, the study of Josephson effect in high-T C superconducting ͑HTS͒ junctions attracted a lot of interest. A while ago, a simple formula for the Josephson current of d-wave superconductor/insulator/d-wave superconductor ͑DID͒ junctions was proposed by Sigrist and Rice ͑SR͒. 5 According to the SR formula, the Josephson current is proportional to cos 2␣ cos 2␤, where the ␣͑␤͒ denotes the angle between the normal to the interface and the crystal axis of the left͑right͒ d-wave superconductor. 5 Although the SR formula can explain experiments with the so-called junctions, 1,2 this formula does not take into account the effect of midgap Andreev resonant states ͑MARS͒ formed at junction interfaces. 6,7 Actually, as shown in Ref. 8, SR formula does not work in ballistic d-wave junctions for ␣ 0 and ␤ 0 where MARS influence severely the charge transport at low temperatures. It was shown both theoretically 9,10 and experimentally 11,12 that MARS induce a nonmonotonic temperature dependence of the maximum Josephson current in DID junctions. On the other hand, SR formula has been extensively used to analyze experiments with various types of HTS Josephson junctions. [13][14][15] Experiments with HTS junctions are of high importance for basic understanding of high-T c superconductivity since they may provide information on possible subdominant admixtures to the d-wave symmetry. [16][17][18] Therefore it is of fundamental interest to understand the physical mechanisms that determine the angular dependence of Josephson current in HTS junctions. For this reason, the determination of the conditions of applicability of the SR formula is an important issue which is addressed in the present paper.In the following, we study the Josephson current in D /DN/I /DN/D junctions, where DN denotes diffusive normal metal and could be formed between the insulator and d-wave superconductors. The calculations are based on the quasiclassical Green's function method applicable to unconventional superconductor junctions. 19,20 We find that the resulting Josephson current in D /DN/I /DN/D junctions is well fitted by the SR formula. Near the transi...

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Angular dependence of Josephson currents in unconventional superconducting junctions

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“…1,2,11 In DID junctions, nonmonotonic temperature dependence of critical current [12][13][14][15][16] occurs due to the formation of midgap Andreev resonant states ͑MARSs͒ at the interface. 17 The MARSs stem from sign change of pair potentials of d-wave superconductors.…”

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Quantitative model for theICRproduct ind-wave Josephson junctions

et al. 2007

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We study theoretically the Josephson effect in d-wave superconductor/diffusive normal metal/insulator/ diffusive normal metal/d-wave superconductor ͑D/DN/I/DN/D͒ junctions. This model aims to describe practical junctions in high-T C cuprate superconductors, in which the product of the critical Josephson current ͑I C ͒ and the normal state resistance ͑R͒ ͑the so-called I C R product͒ is very small compared to the prediction of the standard theory for clean d-wave superconductor/insulator/d-wave superconductor ͑DID͒ junctions. We show that the I C R product in D/DN/I/DN/D junctions can be much smaller than that in DID junctions. The proposed theory describes the behavior of I C R products quantitatively in high-T C cuprate junctions. DOI: 10.1103/PhysRevB.76.052508 PACS number͑s͒: 74.20.Rp, 74.50.ϩr, 74.70.Kn Josephson effect in high-T C superconductors has attracted much attention 1,2 because of its potential applications in future technologies. 3 In particular, applications in electronics, such as the single-flux quantum devices, are extremely promising, since the operating frequency is proportional to the product of the critical Josephson current ͑I C ͒ and the normal state resistance ͑R͒ ͑the so-called I C R product͒ which is approximately proportional to the superconductivity critical temperature. 4 However, almost all experimental data for high-T C Josephson junctions fabricated so far have shown I C R values much smaller than those predicted by the standard theory, irrespective of what kind of junctions they are. 5,6 This strongly suggests that the interfaces in the cuprates are intrinsically pair breaking. Several models were proposed which treat this issue. 7-10 However, the situation has not been described so far in a quantitative manner.One possibility addressed in the present Brief Report and not investigated before is that superconductivity is destroyed near the interface in d-wave superconductor/insulator/ d-wave superconductor ͑DID͒ junctions, where diffusive normal metal ͑DN͒ regions are induced. Thus, DID junctions turn into d-wave superconductor/diffusive normal metal/ insulator/diffusive normal metal/d-wave superconductor ͑D/ DN/I/DN/D͒ junctions ͑see Fig. 1͒. In these junctions, I C R product can be much smaller than that in DID junctions. In this Brief Report, we will explore this possibility and provide a quantitative model which is compared to the experimental data.The Josephson effect is a phase-sensitive phenomenon and thus depends strongly on a superconducting pairing symmetry. 1,2,11 In DID junctions, nonmonotonic temperature dependence of critical current 12-16 occurs due to the formation of midgap Andreev resonant states ͑MARSs͒ at the interface. 17 The MARSs stem from sign change of pair potentials of d-wave superconductors. 18 It was also predicted that MARSs strongly enhance the Josephson current at low temperatures. 13 On the other hand, in Josephson junctions with DN, the role of the MARSs changes.In superconductor/diffusive normal metal/superconductor

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“…c T T The first situation was actually observed in YBa 2 Cu 3 O 7-δ grain-boundary Josephson junctions [53]. The second possibility was most probably realized in YBa 2 Cu 3 O 7-δ bicrystal grainboundary junctions [56].…”

Section: ′ γ γ θmentioning

confidence: 93%

“…However, its connection to the electrode orientation remained obscure. An extremely weak nonmonotonic behavior resembling the transition between the clean and rough limits in the ASJ scenario was found in grain-boundary YBa 2 Cu 3 O 7-δ junctions [53,56]. Other studies of symmetric (S-I-S or S-N-S) junctions [51,52,55] I T may be nonmonotonic owing to the well-known tunnel directionality [25,[30][31][32][33][34][35][36][37][38], with the influence of the latter varying as the interlayer thickness changes.…”

Section: Introductionmentioning

confidence: 97%

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Anomalous temperature dependence of the stationary Josephson tunnel current in junctions between d-wave superconductors

Gabovich

Войтенко

2014

Low Temperature Physics

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Stationary Josephson current I c between d-wave superconductors was calculated for superconductorinsulator-superconductor structures with various rotations of crystals relatively to each other and the junction plane. The directionality of tunneling was taken into account. It was demonstrated that the temperature, T, dependences of I c can become nonmonotonic for certain electrode orientations due to the T-dependent ratio between the contributions of positive and negative I c components. This model gives an explanation to the effect observed in junctions involving cuprates and is an alternative to the well-known scenario that makes allowance for Andreev-Saint-James zero-energy levels.

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Evidence of midgap-state-mediated transport in 45° symmetric [001] tiltYBa2Cu3O7−xbi

Cited by 52 publications

References 31 publications

Angular dependence of Josephson currents in unconventional superconducting junctions

Angular dependence of Josephson currents in unconventional superconducting junctions

Quantitative model for theICRproduct ind-wave Josephson junctions

Anomalous temperature dependence of the stationary Josephson tunnel current in junctions between d-wave superconductors

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