Josephson junctions incorporating a conical magnetic holmium interlayer

Witt, J. D. S.; Robinson, Jason W. A.; Blamire, M. G.

doi:10.1103/physrevb.85.184526

Cited by 38 publications

(38 citation statements)

References 42 publications

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“…9). Even if we assume that exchange coupling with Ho introduces additional domain walls into the Py, given the high saturation field of Ho thin films (B4 T) 19,31 the domain configuration would hardly change in the field range investigated and so we would expect to see a monotonic increase in resistance with field rather than a sharp switching as observed in our data. Moreover, the asymmetry in the resistance peaks in R-H for the spin valve without Ho clearly shows that R-H reflects the exchange bias observed in the M-H loop, and thus the magnetic state of the spin valve is the underlying factor responsible for the observed resistance peaks.…”

Section: Discussionmentioning

confidence: 39%

“…More direct evidence for the generation of triplet pairing was obtained from S-F-S Josephson junctions in which, if interfacial spin-mixer layers were present, supercurrents could be measured through F-layer thicknesses much larger than the singlet coherence length [15][16][17][18][19][20][21][22][23] . As spin-one triplet pairs, unlike singlet pairs, can carry spin, these results mean that combining superconducting and spin electronics (superconducting spintronics) opens up real potential for practical lowtemperature applications 24 .…”

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confidence: 99%

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Evidence for spin selectivity of triplet pairs in superconducting spin valves

et al. 2014

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Spin selectivity in a ferromagnet results from a difference in the density of up-and down-spin electrons at the Fermi energy as a consequence of which the scattering rates depend on the spin orientation of the electrons. This property is utilized in spintronics to control the flow of electrons by ferromagnets in a ferromagnet (F1)/normal metal (N)/ferromagnet (F2) spin valve, where F1 acts as the polarizer and F2 the analyser. The feasibility of superconducting spintronics depends on the spin sensitivity of ferromagnets to the spin of the equal spintriplet Cooper pairs, which arise in superconductor (S)-ferromagnet (F) heterostructures with magnetic inhomogeneity at the S-F interface. Here we report a critical temperature dependence on magnetic configuration in current-in-plane F-S-F spin valves with a holmium spin mixer at the S-F interface providing evidence of a spin selectivity of the ferromagnets to the spin of the triplet Cooper pairs.

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Section: Discussionmentioning

confidence: 39%

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confidence: 99%

Evidence for spin selectivity of triplet pairs in superconducting spin valves

et al. 2014

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“…We have used the definitions of the Dyakonov-Perel spin relaxation tensor Γ ab and the diffusive spin precession tensor C ab k presented in Eqs. (7) and (8). In the most general SO coupling, one can show, that the structure of Eqs.…”

Section: The Singlet-triplet Conversion In Diffusive S/f Structumentioning

confidence: 94%

Spin-orbit coupling as a source of long-range triplet proximity effect in superconductor-ferromagnet hybrid structures

2014

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We investigate the proximity effect in diffusive superconducting hybrid structures with a spin-orbit (SO) coupling. Our study is focused on the singlet-triplet conversion and the generation of long-range superconducting correlations in ferromagnetic elements. We derive the quasiclassical equations for the Green's functions including the SO coupling terms in form of a background SU(2) field. With the help of these equations, we first present an interesting complete analogy between the spin diffusion process in normal metals and the generation of the triplet components of the condensate in a diffusive superconducting structure in the presence of SO coupling. From this analogy it turns out naturally that the SO coupling is an additional source of the long-range triplet component (LRTC) besides the magnetic inhomogeneities studied in the past. This analogy opens a range of possibilities for the generation and manipulation of the triplet condensate in hybrid structures. In particular we demonstrate that a normal metal with a SO coupling can be used as source of LRTC if attached to a S/F bilayer. We also demonstrate an explicit connection between an inhomogeneous exchange field and SO coupling mechanisms for the generation of the LRTC and establish the conditions for the appearance of the LRTC in different geometries. Our work gives a global description of the singlet-triplet conversion in hybrids structures in terms of generic spin-fields and our results are particularly important for the understanding of the physics underlying spintronic devices with superconductors.

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“…For example, consider a S-F -F-F -S Josephson junction [7]: If the F and F layer magnetizations are collinearly aligned, spin-zero triplet pairs form which, like singlet pairs, are short ranged [8] with a coherence length in F metals of only a few nanometers (Ni [9][10][11][12], NiFe [13,14], Co [11,15,16], and Fe [17,18]). However, if F and F layer magnetizations are noncollinearly aligned spin-one triplet pairs form and the coherence length is greatly extended [19][20][21][22][23][24][25][26][27]. See also spectroscopic works on triplet S-F structures in Refs.…”

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Giant triplet proximity effect in superconducting pseudo spin valves with engineered anisotropy

et al. 2014

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The proximity coupling of a thin superconducting layer and an inhomogeneous ferromagnet can lead to a significant reduction of the critical temperature due to the generation of spin-polarized triplet Cooper pairs. We report critical temperature measurements of Co/Cu/NiFe(Py)/Cu/Nb superconducting pseudo spin valves (PSVs) in which the magnetization of the soft layer (Py) can be independently rotated in-plane with a magnetic field to create an angle (θ ) between it and the magnetization of Co. Here we observe results consistent with spin-triplet theory and demonstrate large changes in T C up to −120 mK as the Py layer is rotated from 0°(Co and Py are parallel) to 90°(Co and Py are orthogonal), which offers the potential for active control of the superconducting state. The key to this achievement is engineered magnetic anisotropy in Py, which enables well-defined control over the magnetization configuration of the PSV.

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Josephson junctions incorporating a conical magnetic holmium interlayer

Cited by 38 publications

References 42 publications

Evidence for spin selectivity of triplet pairs in superconducting spin valves

Evidence for spin selectivity of triplet pairs in superconducting spin valves

Spin-orbit coupling as a source of long-range triplet proximity effect in superconductor-ferromagnet hybrid structures

Giant triplet proximity effect in superconducting pseudo spin valves with engineered anisotropy

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