Scattering by magnetic and spin-orbit impurities and the Josephson current in superconductor-ferromagnet-superconductor junctions

Bergeret, F. S.; Volkov, A. N.; Efetov, K. B.

doi:10.1103/physrevb.75.184510

Cited by 26 publications

(29 citation statements)

References 32 publications

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“…spin-flip scattering, as seen from Eq. (29). The above analysis emphasizes the importance of distinguishing between different types of spin-dependent scattering in terms of understanding the behaviour of the DOS in a ferromagnet/superconductor bilayer.…”

Section: Anomalous Green's Functionsmentioning

confidence: 99%

“…This may be attributed to the strong suppression of Andreev bound states due to spin-flip scattering processes, which are usually not taken into account in the theoretical treatment (see, however, Ref. 29). To date, there exists no study of the density of states in F/S structures that allows access to both the full range of barrier transparencies and concentration of magnetic impurities.…”

Section: Introductionmentioning

confidence: 99%

“…Parameters such as barrier transparency and magnetic impurities become important in this respect, as they can have crucial impact on the behaviour of the supercurrent in an S/F/S system. To this end, several recent works investigated some aspects of the supercurrent by including magnetic impurities 29,42,43,44,45,46,47 , but restricting themselves to the tunneling limit. Under the opposite simplifying assumption of transparent interfaces, the influence of spin-flip scattering has also been investigated 48 .…”

Section: Introductionmentioning

confidence: 99%

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Role of interface transparency and spin-dependent scattering in diffusive ferromagnet/superconductor heterostructures

2008

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We present a numerical study of the density of states in a ferromagnet/superconductor junction and the Josephson current in a superconductor/ferromagnet/superconductor junction in the diffusive limit by solving the Usadel equation with Nazarov's boundary conditions. Our calculations are valid for an arbitrary interface transparency and arbitrary spin-dependent scattering rate, which allows us to explore the entire proximity-effect regime. We first investigate how the proximity-induced anomalous Green's function affects the density of states in the ferromagnet for three magnitudes of the exchange field h compared to the superconducting gapIn each case, we consider the effect of the barrier transparency and allow for various concentrations of magnetic impurities. We clarify features that may be expected in the various parameter regimes accessible for the ferromagnetic film, with regard to thickness and exchange field. In particular, we address how the zero-energy peak and minigap observed in experiments may be understood in terms of the interplay between the singlet and triplet anomalous Green's function and their dependence on the concentration of magnetic impurities. Our results should serve as a useful tool for quantitative analysis of experimental data. We also investigate the role of the barrier transparency and spin-flip scattering in a superconductor/ferromagnet/superconductor junction. We suggest that such diffusive Josephson junctions with large residual values of the supercurrent at the 0-π transition, where the first harmonic term in the current vanishes, may be used as efficient supercurrentswitching devices. We numerically solve for the Josephson current in such a junction to clarify to what extent this idea may be realized in an experimental setup. It is also found that uniaxial spin-flip scattering has very different effect on the 0-π transition points depending on whether one regards the width-or temperaturedependence of the current. Our theory takes into account vital elements that are necessary to obtain quantitative predictions of the supercurrent in such junctions.

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Section: Anomalous Green's Functionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Role of interface transparency and spin-dependent scattering in diffusive ferromagnet/superconductor heterostructures

2008

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“…The scattering times are labeled here as τ z , τ x , and τ so , where τ z(x) corresponds to the magnetic scattering parallel (perpendicular) to the quantization axis, and τ so is the spin-orbit scattering time. [38][39][40][41] We consider here ferromagnets with a strong uniaxial anisotropy, in which case the magnetic scattering does not couple the spin-up and spin-down electron populations; i.e., the perpendicular fluctuations of the exchange field are suppressed (τ −1 x ∼ 0). Therefore, we will neglect τ x in our consideration and denote τ z as a magnetic scattering time τ m .…”

Section: Model and Basic Equationsmentioning

confidence: 99%

Current-voltage characteristics of tunnel Josephson junctions with a ferromagnetic interlayer

et al. 2011

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We present a quantitative study of the current-voltage characteristics (CVC) of diffusive superconductor/ insulator/ferromagnet/superconductor (SIFS) tunnel Josephson junctions. In order to obtain the CVC we calculate the density of states (DOS) in the F/S bilayer for arbitrary length of the ferromagnetic layer, using quasiclassical theory. For a ferromagnetic layer thickness larger than the characteristic penetration depth of the superconducting condensate into the F layer, we find an analytical expression which agrees with the DOS obtained from a self-consistent numerical method. We discuss general properties of the DOS and its dependence on the parameters of the ferromagnetic layer. In particular we focus our analysis on the DOS oscillations at the Fermi energy. Using the numerically obtained DOS we calculate the corresponding CVC and discuss their properties. Finally, we use CVC to calculate the macroscopic quantum tunneling (MQT) escape rate for the current biased SIFS junctions by taking into account the dissipative correction due to the quasiparticle tunneling. We show that the influence of the quasiparticle dissipation on the macroscopic quantum dynamics of SIFS junctions is small, which is an advantage of SIFS junctions for superconducting qubits applications.

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“…The function g 2 is in the same channel as∆, and thus encodes the s-wave pairing correlations. The g 1 function has more interesting origin -it describes the p-wave, odd-frequency superconducting correlations, induced by boundaries or other inhomogeneities, and disappearing in bulk uniform superconductors [24][25][26][27] . The component g 1 is odd in momentum, therefore its Fermi surface average vanishes identically g 1 = 0.…”

Section: The S-wave Casementioning

confidence: 99%

Long rangep-wave proximity effect into a disordered metal

2015

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We use quasiclassical methods of superconductivity to study the superconducting proximity effect from a topological p-wave superconductor into a disordered quasi-one-dimensional metallic wire. We demonstrate that the corresponding Eilenberger equations with disorder reduce to a closed nonlinear equation for the superconducting component of the matrix Green's function. Remarkably, this equation is formally equivalent to a classical mechanical system (i.e., Newton's equations), with the Green function corresponding to a coordinate of a fictitious particle and the coordinate along the wire corresponding to time. This mapping allows us to obtain exact solutions in the disordered nanowire in terms of elliptic functions. A surprising result that comes out of this solution is that the p-wave superconductivity proximity-induced into the disordered metal remains long-range, decaying as slowly as the conventional s-wave superconductivity. It is also shown that impurity scattering leads to the appearance of a zero-energy peak.

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Scattering by magnetic and spin-orbit impurities and the Josephson current in superconductor-ferromagnet-superconductor junctions

Cited by 26 publications

References 32 publications

Role of interface transparency and spin-dependent scattering in diffusive ferromagnet/superconductor heterostructures

Role of interface transparency and spin-dependent scattering in diffusive ferromagnet/superconductor heterostructures

Current-voltage characteristics of tunnel Josephson junctions with a ferromagnetic interlayer

Long rangep-wave proximity effect into a disordered metal

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