Long range triplet Josephson current and 0−<i>π</i>transitions in tunable domain walls

Baker, Thomas E.; Richie-Halford, Adam; Bill, Andreas

doi:10.1088/1367-2630/16/9/093048

Cited by 17 publications

(45 citation statements)

References 62 publications

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“…22 Finally, the third class of 0 − π transitions involves a mixture and competition of singlet and triplet correlations and was discussed in Ref. 41. Earlier indication of the existence of the third class can be found in the work of Bergeret, Volkov and Efetov in Ref.…”

Section: -20mentioning

confidence: 97%

“…Prior theoretical works have discussed proximity effects in misaligned homogeneous films 1,2,10,21-27 or rotating magnetizations 1,2,10,[28][29][30][31][32][33][34][35][36][37][38][39][40][41] in the clean or the diffusive limit. The results strongly depend on the choice of materials and the width of the layers.…”

Section: -20mentioning

confidence: 99%

“…Particular focus is set on the latter that was proposed as a device to tune and reverse the Josephson current in one single heterostructure. 41 The insight provided by the study of pair correlations allows understanding which linear combination of spin states is dominant and under what circumstances. To this aim, we focus on a discussion of the Gor'kov functions that describe the superconducting pair correlations.…”

Section: -20mentioning

confidence: 99%

“…1. This magnetic bilayer proposed earlier by the authors to vary the Josephson current 41 has the advantage of being magnetically tunable, allowing to change the relative weight of the pair correlations within the same system. The other advantage is that it is experimentally realizable and has been studied at length in the field of magnetism.…”

Section: -20mentioning

confidence: 99%

“…The function φ(x) has been obtained by minimizing the magnetic energy of the bilayer and provides an excellent description of experimentally realized XS domain walls. 41,45 In all figures involving a domain wall we characterize the twist of the magnetization by the relative angle ∆φ = φ(SF) − φ(FS), which is the angle between the magnetization vectors at the SF and FS interfaces. In the case of the exchange spring the easy axis is alongẑ.…”

Section: E the Magnetic Configurationmentioning

confidence: 99%

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Classification of magnetic inhomogeneities and0−πtransitions in superconducting-magnetic hybrid structures

2016

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We present a comparative study of pair correlations and currents through superconductingmagnetic hybrid systems with a particular emphasis on the tunable Bloch domain wall of an exchange spring. This study of the Gor'kov functions contrasts magnetic systems with domain walls that change at discrete points in the magnetic region with those that change continuously throughout. We present results for misaligned homogeneous magnetic multilayers, including spin valves, for discrete domain walls, as well as exchange springs and helical domain walls -such as Holmiumfor the continuous case. Introducing a rotating basis to disentangle the role of singlet and triplet correlations, we demonstrate that substantial amounts of (so-called short range) singlet correlations are generated throughout the magnetic system in a continuous domain wall via the cascade effect. We propose a classification of 0 − π transitions of the Josephson current into three types, according to the predominant pair correlations symmetries involved in the current. Properties of exchange springs for an experimental study of the proposed effects are discussed. The interplay between components of the Gor'kov function that are parallel and perpendicular to the local magnetization lead to a novel prediction about their role in a proximity system with a progressively twisting helix that is experimentally measurable.

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Section: -20mentioning

confidence: 97%

Section: -20mentioning

confidence: 99%

Section: -20mentioning

confidence: 99%

Section: -20mentioning

confidence: 99%

Section: E the Magnetic Configurationmentioning

confidence: 99%

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Classification of magnetic inhomogeneities and0−πtransitions in superconducting-magnetic hybrid structures

2016

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Superconducting spintronics

2015

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Traditional studies that combine spintronics and superconductivity have mainly focused on the injection of spin-polarized quasiparticles into superconducting materials. However, a complete synergy between superconducting and magnetic orders turns out to be possible through the creation of spin-triplet Cooper pairs, which are generated at carefully engineered superconductor interfaces with ferromagnetic materials. Currently, there is intense activity focused on identifying materials combinations that merge superconductivity and spintronics to enhance device functionality and performance. The results look promising: it has been shown, for example, that superconducting order can greatly enhance central effects in spintronics such as spin injection and magnetoresistance. Here, we review the experimental and theoretical advances in this field and provide an outlook for upcoming challenges in superconducting spintronics.At the interface between materials with radically different properties, new physical phenomena can emerge. A classical example of such an interface is that between a superconductor and a ferromagnet where the opposing electron orders destructively interfere; however, it turns out that under the right conditions at a superconductorferromagnet interface both superconductivity and spin-polarization can unite to create a new superconducting state that offers tantalizing possibilities for spin transport in which Joule heating and dissipation are minimized.Spintronics offers the potential for creating circuits in which logic operations controlled by spin currents can be performed faster and more energy efficient [1] than the charge-based equivalent in semiconductor transistor technologies. Spintronics is one of the most active areas of research and while it offers control of spin and charge at the nanometer scale, it has also found sensory applications in hard disk drive read heads via the giant magnetoresistance effect [2,3]. The idea of combining superconductivity with spintronics has historically focused on the net spin-polarization of quasiparticles in superconductors. It is interesting to note that the first spin transport experiments [4-6] involved ferromagnet-superconductor bilayers and predated non-superconducting spin transport experiments [8]. As will be discussed in this review, it is possible to create pseudo-chargeless spin-1/2 excitations in superconductors [7] which have extremely long spin lifetimes.Recently, a more complete synergy between superconductivity and spintronics has been made possible through the discovery of spin-triplet Cooper pairs at superconductor-ferromagnet interfaces. Non-superconducting spin currents are generated by passing charge currents through ferromagnetic materials. As will be explained in this review, spin currents can also be generated by passing supercurrents through ferromagnetic materials. Charge flow within superconductors is carried by Cooper pairs which consist of interacting pairs of electrons [9]. The idea of combining superconducting and magnetic order wa...

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Coexistence and tuning of spin-singlet and triplet transport in spin-filter Josephson junctions

et al. 2022

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The increased capabilities of coupling more and more materials through functional interfaces are paving the way to a series of exciting experiments and extremely advanced devices. Here we focus on the capability of magnetically inhomogeneous superconductor/ferromagnet (S/F) interfaces to generate spin-polarized triplet pairs. We build on previous achievements on spin-filter ferromagnetic Josephson junctions (JJs) and find direct correspondence between neat experimental benchmarks in the temperature behavior of the critical current and theoretical modelling based on microscopic calculations, which allow to determine a posteriori spin-singlet and triplet correlation functions. This kind of combined analysis provides an accurate proof of the coexistence and tunability of singlet and triplet transport. This turns to be a powerful way to model disorder and spin-mixing effects in a JJ to enlarge the space of parameters, which regulate the phenomenology of the Josephson effect and could be applied to a variety of hybrid JJs.

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Long range triplet Josephson current and 0−πtransitions in tunable domain walls

Cited by 17 publications

References 62 publications

Classification of magnetic inhomogeneities and0−πtransitions in superconducting-magnetic hybrid structures

Classification of magnetic inhomogeneities and0−πtransitions in superconducting-magnetic hybrid structures

Superconducting spintronics

Coexistence and tuning of spin-singlet and triplet transport in spin-filter Josephson junctions

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