Josephson effects in iron based superconductors

Seidel, P.

doi:10.1088/0953-2048/24/4/043001

Cited by 94 publications

(66 citation statements)

References 116 publications

(186 reference statements)

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“…Important feature of c-oriented S/I/S p Josephson junction is significant suppression of the magnitude of the Josephson current in the case of long insulating layer (Fig.10,b) compared to the direct contact (Fig.10,a). The suppression of the Josephson current was observed in recent Josephson tunneling experiments in a FeBS 44 .…”

Section: A Current-phase Relation In S/i/sp Junctionsmentioning

confidence: 60%

Josephson current in Fe-based superconducting junctions: Theory and experiment

et al. 2015

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We present theory of dc Josephson effect in contacts between Fe-based and spin-singlet s-wave superconductors. The method is based on the calculation of temperature Green's function in the junction within the tight-binding model. We calculate the phase dependencies of the Josephson current for different orientations of the junction relative to the crystallographic axes of Fe-based superconductor. Further, we consider the dependence of the Josephson current on the thickness of an insulating layer and on temperature. Experimental data for PbIn/Ba1−xKx(FeAs)2 pointcontact Josephson junctions are consistent with theoretical predictions for s± symmetry of an order parameter in this material. The proposed method can be further applied to calculations of the dc Josephson current in contacts with other new unconventional multiorbital superconductors, such as Sr2RuO4 and superconducting topological insulator CuxBi2Se3.

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Section: A Current-phase Relation In S/i/sp Junctionsmentioning

confidence: 60%

Josephson current in Fe-based superconducting junctions: Theory and experiment

et al. 2015

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“…The iteration loop was stopped when the difference between the input and the calculated order parameters was less than 1 × 10 −5 . The bulk pairing amplitude ∆ 0 corresponding to given values of µ 0 and U can be calculated by solving the self-consistency equation (10). This was done iterating equation (10) in a 100×100 lattice with periodic boundary conditions until the input and the calculated order parameters was less than 1 × 10 −5 .…”

Section: Appendix A: Magnetic Fluxmentioning

confidence: 99%

Effects of order parameter self-consistency in as±−sjunction

2016

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The properties of Josephson tunneling between a single band s-wave superconductor and a two band s± superconductor are studied, in relation to recent experiments involving iron-based superconductors. We study both a single junction and a loop consisting of two junctions. In both cases, the relative phase between the order parameters of the two superconductors is tuned and the energy of the system is calculated. In a single junction, we find four types of behaviors characterized by the location of minima in the energy/phase relations. These phases include a newly found double minimum junction which appears only when the order parameters are treated self-consistently. We analyze the loop geometry setup in light of our results for a single junction, where the phase difference in the junctions is controlled by a threaded flux. We find four types of energy/flux relations. These include states for which the energy is minimized when the threaded flux is an integer or half integer number of flux quanta, a time reversal broken state and a meta-stable state.

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“…No model has got an unambiguous experimental confirmation yet, thus making the main issues still unanswered. For example, the experimentally determined BCS ratio in Ba-122 family varies by a factor of six [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], for a review, see 12,34]. A possible reason is the strong out-of-plane gap anisotropy in k-space which seems to "smear" the gap values obtained in bulk probes, and a sensitivity-to-surface of the superconducting properties.…”

Section: Introductionmentioning

confidence: 99%

On the structure of the superconducting order parameter in high-temperature Fe-based superconductors

Kuzmicheva¹,

Muratov²,

Kuzmichev³

et al. 2017

Phys.-Usp.

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We discuss the synthesis, characterization, and comprehensive study of Ba-122 single crystals with various substitutions and various superconducting transition temperatures. We use five complementary techniques to obtain a self-consistent set of data on the superconducting properties of Ba-122. A major conclusion of our work is the coexistence of two superconducting condensates differing in the electron–boson coupling strength. The two gaps that develop in distinct Fermi surface sheets are nodeless in the kxky plane and exhibit s-wave symmetry; the two-band model suffices for the description of the main parameters of the superconducting state. A moderate interband coupling and a considerable Coulomb repulsion in the description of the two-gap superconducting state of barium pnictides favor the s++ model.

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Josephson effects in iron based superconductors

Cited by 94 publications

References 116 publications

Josephson current in Fe-based superconducting junctions: Theory and experiment

Josephson current in Fe-based superconducting junctions: Theory and experiment

Effects of order parameter self-consistency in as±−sjunction

On the structure of the superconducting order parameter in high-temperature Fe-based superconductors

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