Superconducting triplet spin valve

Fominov, Ya. V.; Golubov, A. A.; Karminskaya, T. Yu.; Kupriyanov, M. Yu.; Деминов, Р. Г.; Тагиров, Л. Р.

doi:10.1134/s002136401006010x

Cited by 177 publications

(139 citation statements)

References 16 publications

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“…As spin-one triplet pairs are immune to pair breaking by the exchange field in F, the proximity effect coupling between S and F layers is enhanced. As with the conventional superconductor-normal metal proximity effect, the increased 'leakage' of pairs from the S layer should reduce the singlet pair amplitude within it and hence decrease the T C of the structure 12 . A number of experiments have been performed to test these predictions: for example, in S-F 0 -F structures, both Leksin et al 13 and Zdravkov et al 14 recently demonstrated a minimum in T C when the F and F 0 layers were orthogonal-the configuration that theoretically maximizes singlet-triplet pair conversion.…”

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confidence: 99%

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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confidence: 99%

Evidence for spin selectivity of triplet pairs in superconducting spin valves

et al. 2014

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“…Recent theoretical studies (see, for example,reviews [2][3][4][5][6][7][8]) have predicted the generation of a long-range triplet component of a superconducting condensate in S/F-structures. As follows from the theory proposed by Fominov et al [9], the presence of a minimum of the superconducting transition temperature T c in e-mail: kamandi@mail.ru the vicinity of the orthogonal configuration of the magnetizations clearly indicates the generation of the longrange triplet component. We have experimentally confirmed the existence of the long-range triplet component for the CoO x /Fe1/Cu/Fe2/Pb superconducting spin-valve structure [10].…”

Section: Introductionmentioning

confidence: 88%

“…The significant discrepancy between theory and experiment can be caused by two factors. In the theory proposed by Fominov et al [9], the F-layers were represented by weak ferromagnets, whereas permalloy is not ferromagnetic. In addition, we ignored the limitation of the transparency of the Py1/Cu/Py2 interface, as was done in the theoretical studies of Deminov et al [21,22], because, in our case, this parameter would be free.…”

Section: Discussion Of Experimental Resultsmentioning

confidence: 99%

“…Here, for the first time, we carried out a direct comparative analysis of the theoretically calculated and experimentally measured values of the superconducting transition temperature T c . For the theoretical calculation of the dependence T c (α), we used the theory proposed by Fominov and his colleagues (see [9]) for the case of an arbitrary transparency of the F2/S interface (see [17,20]). The result of this calculation is represented by the solid line in Fig.…”

Section: Discussion Of Experimental Resultsmentioning

confidence: 99%

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Isolation of proximity-induced triplet pairing channel in a superconductor/ferromagnet spin valve

et al. 2018

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Abstract. In the present work we have studied the proximity-induced superconducting triplet pairing in CoO x /Py1/Cu/Py2/Cu/Pb spin-valve structure (where Py = Ni 0.81 Fe 0.19 ).For CoO x (3 nm)/Py(3 nm)/Cu(4 nm)/Py(0.6 nm)/Cu(2 nm)/Pb(70 nm) we have studied the dependence of the T c on the angle α between the direction of the cooling field and the external field both applied in the plane of the sample. We obtained that the T c does not change monotonically with the angle but passes through a minimum. To observe an "isolated" triplet spin-valve effect we exploited the oscillatory feature of the magnitude of the ordinary spin-valve effect ∆T c in the dependence of the Py2-layer thickness d Py2 . We determined the value of d Py2 at which ∆T c caused by the ordinary spin-valve effect is suppressed. This means that the difference in the T c between the antiparallel and parallel mutual orientation of magnetizations of the Py1 and Py2 layers is zero. For such a sample a "pure" triplet spin-valve effect which causes the minimum in T c at the orthogonal configuration of magnetizations has been observed.

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“…A number of implementations of Josephson control elements were proposed recently, among which the structures containing F layers in the weak link region are of greatest interest [1][2][3] . Various types of superconducting spin-valve structures including two or more ferromagnetic layers have been proposed [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] . The mutual orientations, parallel or antiparallel, of magnetizations of the layers determine critical currents and critical temperatures of the structures.…”

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Superconducting phase domains for memory applications

Bakurskiy

Klenov

Soloviev

et al. 2016

Applied Physics Letters

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In this work we study theoretically the properties of S-F/N-sIS type Josephson junctions in the frame of the quasiclassical Usadel formalism. The structure consists of two superconducting electrodes (S), a tunnel barrier (I), a combined normal metal/ferromagnet (N/F) interlayer and a thin superconducting film (s). We demonstrate the breakdown of a spatial uniformity of the superconducting order in the s-film and its decomposition into domains with a phase shift π . The effect is sensitive to the thickness of the s layer and the widths of the F and N films in the direction along the sIS interface. We predict the existence of a regime where the structure has two energy minima and can be switched between them by an electric current injected laterally into the structure. The state of the system can be non-destructively read by an electric current flowing across the junction. PACS numbers: 74.45.+c, 74.50.+r, 74.78.Fk, 85.25.Cp Josephson junctions containing normal (N) and ferromagnetic (F) materials in a weak link region are currently the subject of intense research. An interest in such structures is due to the possibility of their use as control elements of superconductor memory compatible with Single Flux Quantum (SFQ) logic. A number of implementations of Josephson control elements were proposed recently, among which the structures containing F layers in the weak link region are of greatest interest 1-3 . Various types of superconducting spin-valve structures including two or more ferromagnetic layers have been proposed [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] . The mutual orientations, parallel or antiparallel, of magnetizations of the layers determine critical currents and critical temperatures of the structures. Recently, it was proposed to apply the phenomenon of triplet superconductivity in spin-valve devices with noncollinear magnetization of the layers [19][20][21][22][23][24][25][26][27] . The problem of small characteristic voltage I C R N in these structures was solved by using an additional tunnel barrier connected through a thin superconducting spacer [28][29][30][31] . However, to control an operation of these devices, the application of magnetic fields or strong spin-polarized currents is necessary in order to switch the structure to a different state. Such control requires the use of additional external circuits resulting in restriction of possible memory density. Moreover, characteristic operational times of such devices are limited by relatively slow processes of the remagnetization of the ferromagnetic layers.In this work we propose a S-N/F-s-I-S control unit for a superconducting memory cell (Fig.1) based on the principles completely different as the suggested earlier. The considered structure consists of the two superconductive electrodes (S) and of the two weak link regions: the tunnel barrier (I) and the metallic (N/F) interlayer. The (N/F) part is formed by the longitudinally oriented normal (N) and ferromagnetic (F) layers. The weak link areas are separated by a thin super...

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Superconducting triplet spin valve

Cited by 177 publications

References 16 publications

Evidence for spin selectivity of triplet pairs in superconducting spin valves

Evidence for spin selectivity of triplet pairs in superconducting spin valves

Isolation of proximity-induced triplet pairing channel in a superconductor/ferromagnet spin valve

Superconducting phase domains for memory applications

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