Pure second harmonic current-phase relation in spin-filter Josephson junctions

Pal, Avradeep; Barber, Z. H.; Robinson, Jason W. A.; Blamire, M. G.

doi:10.1038/ncomms4340

Cited by 69 publications

(76 citation statements)

References 20 publications

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“…In contrast to a Fraunhofer pattern, it does not depend on the geometry of the junction, but on the current-phase relationship of the junction. A sum of different current-phase relationships [22][23][24][25][26][27] …”

Section: Expected Majorana Related Modifications Of the Critical Currmentioning

confidence: 99%

Geometric dependence of Nb-Bi₂Te₃-Nb topological Josephson junction transport parameters

Molenaar

Leusink

Wang

et al. 2014

Supercond. Sci. Technol.

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Superconductor-topological insulator-superconductor Josephson junctions have been fabricated in order to study the width dependence of the critical current, normal state resistance and flux periodicity of the critical current modulation in an external field. Previous literature reports suggest anomalous scaling in topological junctions due to the presence of Majorana bound states. However, for most realized devices, one would expect that trivial π 2 -periodic Andreev levels dominate transport. We also observe anomalous scaling behaviour of junction parameters, but the scaling can be well explained by mere geometric effects, such as the parallel bulk conductivity shunt and flux focusing.

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Section: Expected Majorana Related Modifications Of the Critical Currmentioning

confidence: 99%

Geometric dependence of Nb-Bi₂Te₃-Nb topological Josephson junction transport parameters

Molenaar

Leusink

Wang

et al. 2014

Supercond. Sci. Technol.

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“…Recently, sin 2ϕ behavior has been observed in S/F/S junctions [78], when the ferromagnet is an insulator which has a spin filter effect. Thus to clarify the relevance of our obtained sin 2ϕ dependence to this experimental report is a challenging issue.…”

Section: Discussionmentioning

confidence: 99%

Josephson current in a normal-metal nanowire coupled to a superconductor/ferromagnet/superconductor junction

Ebisu

Taguchi

et al. 2016

Phys. Rev. B

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We consider a superconducting nanowire proximity coupled to a superconductor/ferromagnet/superconductor (S/F/S) junction, where the magnetization penetrates into a superconducting segment in a nanowire decaying as], where n is the site index and the ξ is the decay length. We tune chemical potential and spin-orbit coupling so that the topological superconducting regime hosting the Majorana fermion is realized for long ξ . We find that when ξ becomes shorter, zero energy state at the interface between a superconductor and a ferromagnet splits into two states at nonzero energy. Accordingly, the behavior of the Josephson current is drastically changed due to this "zero mode-nonzero mode crossover." By tuning the model parameters, we find an almost second-harmonic current-phase relation sin 2ϕ, where ϕ is the phase difference of the junction. Based on the analysis of Andreev bound state (ABS), we clarify that the current-phase relation is determined by coupling of the states within the energy gap. We find that the emergence of crossing points of ABS is a key ingredient to generate sin 2ϕ dependence in the current-phase relation. We further study both the energy and ϕ dependence of pair amplitudes in the ferromagnetic region. For large ξ , an odd-frequency spin-triplet s-wave component is dominant. The magnitude of the odd-frequency pair amplitude is enhanced at the energy level of ABS.

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“…The latter include both ferromagnetic insulators such as EuO or GdN 4, 5 , with spin-polarizations ranging up to 90%, and half-metallic ferromagnets such as CrO 2 and La 2/3 Ca 1/3 MnO 3 (LCMO) 6–8 . In ref.…”

Section: Introductionmentioning

confidence: 99%

Triplet Cooper pairs induced in diffusive s-wave superconductors interfaced with strongly spin-polarized magnetic insulators or half-metallic ferromagnets

Ouassou

Pal

Blamire

et al. 2017

Sci Rep

Self Cite

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Interfacing superconductors with strongly spin-polarized magnetic materials opens the possibility to discover new spintronic devices in which spin-triplet Cooper pairs play a key role. Motivated by the recent derivation of spin-polarized quasiclassical boundary conditions capable of describing such a scenario in the diffusive limit, we consider the emergent physics in hybrid structures comprised of a conventional s-wave superconductor (e.g. Nb, Al) and either strongly spin-polarized ferromagnetic insulators (e.g. EuO, GdN) or halfmetallic ferromagnets (e.g. CrO2, LCMO). In contrast to most previous works, we focus on how the superconductor itself is influenced by the proximity effect, and how the generated triplet Cooper pairs manifest themselves in the self-consistently computed density of states (DOS) and the superconducting critical temperature T c. We provide a comprehensive treatment of how the superconductor and its properties are affected by the triplet pairs, demonstrating that our theory can reproduce the recent observation of an unusually large zero-energy peak in a superconductor interfaced with a half-metal, which even exceeds the normal-state DOS. We also discuss the recent observation of a large superconducting spin-valve effect with a T c change ~1 K in superconductor/half-metal structures, in which case our results indicate that the experiment cannot be explained fully by a long-ranged triplet proximity effect.

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Pure second harmonic current-phase relation in spin-filter Josephson junctions

Cited by 69 publications

References 20 publications

Geometric dependence of Nb-Bi₂Te₃-Nb topological Josephson junction transport parameters

Geometric dependence of Nb-Bi₂Te₃-Nb topological Josephson junction transport parameters

Josephson current in a normal-metal nanowire coupled to a superconductor/ferromagnet/superconductor junction

Triplet Cooper pairs induced in diffusive s-wave superconductors interfaced with strongly spin-polarized magnetic insulators or half-metallic ferromagnets

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Pure second harmonic current-phase relation in spin-filter Josephson junctions

Cited by 69 publications

References 20 publications

Geometric dependence of Nb-Bi2Te3-Nb topological Josephson junction transport parameters

Geometric dependence of Nb-Bi2Te3-Nb topological Josephson junction transport parameters

Josephson current in a normal-metal nanowire coupled to a superconductor/ferromagnet/superconductor junction

Triplet Cooper pairs induced in diffusive s-wave superconductors interfaced with strongly spin-polarized magnetic insulators or half-metallic ferromagnets

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Geometric dependence of Nb-Bi₂Te₃-Nb topological Josephson junction transport parameters

Geometric dependence of Nb-Bi₂Te₃-Nb topological Josephson junction transport parameters