Josephson current through superconductor/diffusive-normal-metal/superconductor junctions: Interference effects governed by pairing symmetry

Asano, Yasuhiro; Tanaka, Yukio; Yokoyama, Takehito; Kashiwaya, Satoshi

doi:10.1103/physrevb.74.064507

Cited by 30 publications

(15 citation statements)

References 48 publications

(54 reference statements)

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“…The chiral p term, of the total OP, is mainly transformed in p y for low transparency barriers. Theory shows that in p y - p y junctions the critical current becomes strongly suppressed even for a slight increase of scattering in the junction 33 . This is therefore consistent with the observed reduction, of orders of magnitude in I C , after thermal cycling.…”

Section: Discussionmentioning

confidence: 99%

Induced unconventional superconductivity on the surface states of Bi2Te3 topological insulator

et al. 2017

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Topological superconductivity is central to a variety of novel phenomena involving the interplay between topologically ordered phases and broken-symmetry states. The key ingredient is an unconventional order parameter, with an orbital component containing a chiral p x + ip y wave term. Here we present phase-sensitive measurements, based on the quantum interference in nanoscale Josephson junctions, realized by using Bi2Te3 topological insulator. We demonstrate that the induced superconductivity is unconventional and consistent with a sign-changing order parameter, such as a chiral p x + ip y component. The magnetic field pattern of the junctions shows a dip at zero externally applied magnetic field, which is an incontrovertible signature of the simultaneous existence of 0 and π coupling within the junction, inherent to a non trivial order parameter phase. The nano-textured morphology of the Bi2Te3 flakes, and the dramatic role played by thermal strain are the surprising key factors for the display of an unconventional induced order parameter.

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Section: Discussionmentioning

confidence: 99%

Induced unconventional superconductivity on the surface states of Bi2Te3 topological insulator

et al. 2017

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“…Thus, spin triplet pairs in s-wave superconductors with even spatial symmetry must have a pair correlation function that is odd in the time argument, called odd frequency spin triplets [5,11]. Triplet pairs are created at interfaces between superconductors and ferromagnetic materials, and their properties have been studied theoretically intensively [12,13]. When a single magnetisation direction is present, solely m = 0 triplet pairs ( 1 √ 2 [| ↑↓ + | ↓↑ ]) are created by spin-mixing, i.e., spin-dependent phase shifts for the electrons scattering at this interface [11].…”

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confidence: 99%

Creation of equal-spin triplet superconductivity at the Al/EuS interface

et al. 2018

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In conventional superconductors, electrons of opposite spins are bound into Cooper pairs. However, when the superconductor is in contact with a non-uniformly ordered ferromagnet, an exotic type of superconductivity can appear at the interface, with electrons bound into three possible spin-triplet states. Triplet pairs with equal spin play a vital role in low-dissipation spintronics. Despite the observation of supercurrents through ferromagnets, spectroscopic evidence for the existence of equal-spin triplet pairs is still missing. Here we show a theoretical model that reveals a characteristic gap structure in the quasiparticle density of states which provides a unique signature for the presence of equal-spin triplet pairs. By scanning tunnelling spectroscopy we measure the local density of states to reveal the spin configuration of triplet pairs. We demonstrate that the Al/EuS interface causes strong and tunable spin-mixing by virtue of its spin-dependent transmission.

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“…A remarkable feature of the flat-band MBSs is that they have an extensive degeneracy at the Fermi level, unlike other forms of MBSs. Accordingly, the flat-band MBSs of the p x -wave SC affect low-energy electromagnetic responses drastically and cause various anomalies: a prominent zero-bias conductance peak in normal-metal/SC junctions [18][19][20][21][22][23][24][25][26][27], a fractional current-phase relationship in two-dimensional Josephson junctions [28][29][30][31][32][33], and a distinct paramagnetic Meissner response to magnetic fields [34][35][36].…”

Section: Introductionmentioning

confidence: 99%

Flat-band Majorana bound states in topological Josephson junctions

Oshima¹,

Ikegaya²,

Schnyder³

et al. 2021

Preprint

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Nodal topological superconductors characterized by px-wave pairing symmetry host flat-band Majorana bound states causing drastic anomalies in low-energy electromagnetic responses. Nevertheless, the study of flat-band Majorana bound states has been at a standstill owing to a serious lack of candidate materials for px-wave superconductors. In this paper, by expanding a scheme of planar topological Josephson junctions, we propose a promising device realizing an effective px-wave superconductor. Specifically, we consider a three-dimensional Josephson junction consisting of a thin-film semiconductor hosting a persistent spin-helix state and two conventional s-wave superconductors. We analytically obtain a topological phase diagram and numerically demonstrate the emergence of flat-band Majorana bound states by calculating the local density of states.

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Josephson current through superconductor/diffusive-normal-metal/superconductor junctions: Interference effects governed by pairing symmetry

Cited by 30 publications

References 48 publications

Induced unconventional superconductivity on the surface states of Bi2Te3 topological insulator

Induced unconventional superconductivity on the surface states of Bi2Te3 topological insulator

Creation of equal-spin triplet superconductivity at the Al/EuS interface

Flat-band Majorana bound states in topological Josephson junctions

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