Inverse proximity effect and influence of disorder on triplet supercurrents in strongly spin-polarized ferromagnets

Grein, Roland; Löfwander, Tomas; Eschrig, Matthias

doi:10.1103/physrevb.88.054502

Cited by 33 publications

(21 citation statements)

References 39 publications

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“…The pairing interaction and the cutoff energy are eliminated in favor of the superconducting transition temperature T c (see for example ref. 66 ) as…”

Section: Methodsmentioning

confidence: 99%

Broken translational symmetry at edges of high-temperature superconductors

et al. 2018

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Flat bands of zero-energy states at the edges of quantum materials have a topological origin. However, their presence is energetically unfavorable. If there is a mechanism to shift the band to finite energies, a phase transition can occur. Here we study high-temperature superconductors hosting flat bands of midgap Andreev surface states. In a second-order phase transition at roughly a fifth of the superconducting transition temperature, time-reversal symmetry and continuous translational symmetry along the edge are spontaneously broken. In an external magnetic field, only translational symmetry is broken. We identify the order parameter as the superfluid momentum ps, that forms a planar vector field with defects, including edge sources and sinks. The critical points of the vector field satisfy a generalized Poincaré-Hopf theorem, relating the sum of Poincaré indices to the Euler characteristic of the system.

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“…The pairing interaction and the cutoff energy are eliminated in favor of the superconducting transition temperature T c (see for example ref. 66 ) as…”

Section: Methodsmentioning

confidence: 99%

Broken translational symmetry at edges of high-temperature superconductors

et al. 2018

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“…Therefore, the inverse proximity effect decays on the short coherence length scale ξ 0 independently of ϑ. [37][38][39]41 We emphasize that the spectral contribution M eq (z) exists at zero bias and is a consequence of the interface-induced difference between the spin-resolved densities of states, and no direct quasiparticle injection is needed. Therefore the decay of this contribution is governed by a healing length of a superconductor, which is ξ 0 .…”

Section: A Spectral Part Of Spin Imbalance: Inverse Proximity Effectmentioning

confidence: 92%

Spin imbalance in hybrid superconducting structures with spin-active interfaces

Shevtsov

Löfwander

2014

Phys. Rev. B

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We consider a heterostructure consisting of a normal metal and a superconductor separated by a spin-active interface. At finite bias voltages, spin-filtering and spin-mixing effects at the interface allow for an induced magnetization (spin imbalance) on the superconducting side of the junction, which relaxes to zero in the bulk. Such interfaces are also known to host a pair of in-gap Andreev bound states which were recently observed experimentally. We show that these states are responsible for the dominant contribution to the induced spin imbalance close to the interface. Motivated by recent experiments on spin-charge density separation in superconducting aluminum wires, we propose an alternative way to observe spin imbalance without applying an external magnetic field. We also suggest that the peculiar dependence of the spin imbalance on the applied bias voltage permits an indirect bound state spectroscopy.

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“…which is just equation (2.12) rotated in spin-space by the spherical angles α and ϕ. For the equalspin coherence functions (or pair amplitudes) in F follows up to leading order in the misalignent angles α, β (denoting azimuthal angle in spin space, which play an important role in Josephson structures with halfmetallic ferromagnets [87,89] and with strongly spin-polarized ferromagnets when two interfaces with different azimuthal angles ϕ 1 and ϕ 2 are involved [106,107].…”

Section: (B) Pair Amplitudes At An S-fi-f Interfacementioning

confidence: 99%

“…The inverse proximity effect transfers magnetization from the ferromagnet into the superconductor or across a superconductor. For strongly spin-polarized systems this occurs as a result of spin-mixing phases [89,107]. A combination of non-local effects in S-F structures with non-equilibrium Andreev interferometer geometries, in analogy to experiments in S-N structures [155,156], seems to be another exciting avenue for future applications [157].…”

Section: (B) Andreev Bound States In Non-local Geometrymentioning

confidence: 99%

Theory of Andreev bound states in S-F-S junctions and S-F proximity devices

Eschrig¹

2018

Phil. Trans. R. Soc. A.

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Andreev bound states are an expression of quantum coherence between particles and holes in hybrid structures composed of superconducting and non-superconducting metallic parts. Their spectrum carries important information on the nature of the pairing, and determines the current in Josephson devices. Here, I focus on Andreev bound states in systems involving superconductors and ferromagnets with strong spin-polarization. I provide a general framework for non-local Andreev phenomena in such structures in terms of coherence functions, and show how the latter link wave function and Green-function based theories.This article is part of the theme issue 'Andreev bound states'.

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Inverse proximity effect and influence of disorder on triplet supercurrents in strongly spin-polarized ferromagnets

Cited by 33 publications

References 39 publications

Broken translational symmetry at edges of high-temperature superconductors

Broken translational symmetry at edges of high-temperature superconductors

Spin imbalance in hybrid superconducting structures with spin-active interfaces

Theory of Andreev bound states in S-F-S junctions and S-F proximity devices

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