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

Burmistrova, A. V.; Devyatov, I. A.; Golubov, A. A.; Yada, Keiji; Tanaka, Yukio; Tortello, Mauro; Gonnelli, Renato; Степанов, В. А.; Ding, Xiaxin; Wen, H. H.; Greene, L. H.

doi:10.1103/physrevb.91.214501

Cited by 32 publications

(45 citation statements)

References 62 publications

(106 reference statements)

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“…The main difficulty for such a multiband superconductor is the need to design an experimental geometry in such a way that the current through one contact is dominated by carriers having positive sign of the order parameter and in the other contact the opposite case occurs. The isotropic nature of the s wave fails the effort in this direction; however, the extended s-wave nature comes directly under the realm of such experimental investigation [35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Quasiparticle interference in multiband superconductors with strong coupling

et al. 2017

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We develop a theory of the quasiparticle interference (QPI) in multiband superconductors based on the strong-coupling Eliashberg approach within the Born approximation. In the framework of this theory, we study dependencies of the QPI response function in the multiband superconductors with the nodeless s-wave superconductive order parameter. We pay special attention to the difference in the quasiparticle scattering between the bands having the same and opposite signs of the order parameter. We show that at the momentum values close to the momentum transfer between two bands, the energy dependence of the quasiparticle interference response function has three singularities. Two of these correspond to the values of the gap functions and the third one depends on both the gaps and the transfer momentum. We argue that only the singularity near the smallest band gap may be used as a universal tool to distinguish between the s ++ and s ± order parameters. The robustness of the sign of the response function peak near the smaller gap value, irrespective of the change in parameters, in both the symmetry cases is a promising feature that can be harnessed experimentally.

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Section: Introductionmentioning

confidence: 99%

Quasiparticle interference in multiband superconductors with strong coupling

et al. 2017

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“…The setup consisted of a niobium fork making two contacts with a sample of NdFeAsO 0.88 F 0. 12 . This amounts to a loop made of a conventional s-wave superconductor which is connected in two points to an FeSC sample.…”

Section: Introductionmentioning

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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“…Burmistrova et al [41] likewise acquired the boundary conditions in multi-band superconducting systems by extending the tight-binding approach beyond the effective mass approximation and taking into account complex nonparabolic and anisotropic energy spectra, as well as unconventional pairing symmetry. The theory of dc Josephson effect in contacts between iron-based and spin-singlet s-wave SCs is also presented, [42] based on the calculation of temperature Green's function in the junction within the tight-binding mode. The corresponding boundary conditions in the quasiclassical approximation at SC/insulator boundary are also obtained.…”

Section: Modelmentioning

confidence: 99%

Tunable 0–πtransition by interband coupling in iron-based superconductor Josephson junctions

Tao

Liu

et al. 2015

New J. Phys.

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An extended four-component Bogoliubov-de Gennes equation is applied to study the Josephson effect in ballistic limit between either two iron-based superconductors (SCs) or an iron-based SC and a conventional s-wave SC, separated by a normal metal. A 0-π transition as a function of interband coupling strength α is always exhibited, arising from the tuning of mixing between the two trajectories with opposite phases. The novel property can be experimentally used to discriminate the s  -wave pairing symmetry in the iron-based SCs from the s ++ -wave one in MgB 2 . The effect of interface transparency on the 0-π transition is also presented. The 0-π transition as a function of α is wholly distinct from that as a function of barrier strength or temperature in recent theories (Linder et al 2009 Phys. Rev. B 80 020503(R)). The possible experimental probe of the phase-shift effect in iron-based SC Josephson junctions is commented on as well.

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

Cited by 32 publications

References 62 publications

Quasiparticle interference in multiband superconductors with strong coupling

Quasiparticle interference in multiband superconductors with strong coupling

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

Tunable 0–πtransition by interband coupling in iron-based superconductor Josephson junctions

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