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

We report magnetic and superconducting properties of the modified spin valve system CoOx/Fe1/Cu/Fe2/Cu/Pb. Introduction of a Cu interlayer between Fe2 and Pb layers prevents material interdiffusion process, increases the Fe2/Pb interface transparency, stabilizes and enhances properties of the system. This allowed us to perform a comprehensive study of such heterostructures and to present theoretical description of the superconducting spin valve effect and of the manifestation of the long-range triplet component of the superconducting condensate.

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“…Recently for the structure of the spin valve similar to the studied by us an evidence for generation of LRTC was obtained as well [46,47].…”

Section: B Superconducting Spin Valvementioning

confidence: 57%

Superconducting spin-valve effect and triplet superconductivity inCoOx/Fe1/Cu/Fe2/Cu/Pbmultilayer

et al. 2015

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“…Those groups found evidence for spin-triplet generation occurring during the magnetization reversal process while sweeping an external magnetic field. Better control of the magnetic states has been achieved recently by several groups measuring the critical temperature T c of S/F/F trilayers, where generation of spin-triplet correlations results in lowering of T c [21][22][23][24][25][26]. Controlling T c , however, is less likely to be useful for future device applications than controlling supercurrent.…”

mentioning

confidence: 99%

Amplitude Control of the Spin-Triplet Supercurrent inS/F/SJosephson Junctions

Martinez¹,

Pratt²,

Birge³

2016

Phys. Rev. Lett.

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Josephson junctions made with conventional s-wave superconductors and containing multiple layers of ferromagnetic materials can carry spin-triplet supercurrent in the presence of certain types of magnetic inhomogeneity. In junctions containing three ferromagnetic layers, the triplet supercurrent is predicted to be maximal when the magnetizations of adjacent layers are orthogonal, and zero when the magnetizations of any two adjacent layers are parallel. Here we demonstrate on-off control of the spin-triplet supercurrent in such junctions, achieved by rotating the magnetization direction of one of the three layers by 90 • . We obtain "on-off" ratios of 5, 7, and 19 for the supercurrent in the three samples studied so far. These observations directly confirm one of the most salient predictions of the theory, and pave the way for applications of spin-triplet Josephson junctions in the nascent area of "superconducting spintronics."

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“…[5] and ∆T c = 120 mK in Ref. [6]), the full switching between the superconducting and normal states has been realized only in a few cases [7,8] because ∆T c was usually smaller than the width of the superconducting transition δT c .…”

mentioning

confidence: 99%

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

et al. 2016

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We have studied the proximity-induced superconducting triplet pairing in CoOx/Py1/Cu/Py2/Cu/Pb spin-valve structure (where Py = Ni0.81Fe0.19).By optimizing the parameters of this structure we found a triplet-channel assisted full switching between the normal and superconducting states. To observe an "isolated" triplet spin-valve effect we exploited the oscillatory feature of the magnitude of the ordinary spin-valve effect ∆Tc in the dependence of the Py2-layer thickness dP y2. We determined the value of dP y2 at which ∆Tc caused by the ordinary spin-valve effect (the difference in the superconducting transition temperature Tc between the antiparallel and parallel mutual orientation of magnetizations of the Py1 and Py2 layers) is suppressed. For such a sample a "pure" triplet spin-valve effect which causes the minimum in Tc at the orthogonal configuration of magnetizations has been observed.The superconducting spin-valve effect consists of different degree of suppression of superconductivity in the F1/F2/S or F1/S/F2 thin film multilayer constructions at parallel (P) and antiparallel (AP) mutual orientation of magnetizations of the F1 and F2 ferromagnetic layers. The superconducting spin valves based on the superconductor/ferromagnet (S/F) proximity effect offer a playground to explore fundamental aspects of interplay between superconductivity and magnetism and also promise applications as passive devices of the superconducting spintronics. The latter construction should be operational upon application of a small external magnetic field. Many experimental works were performed to confirm this effect for the S/F systems with a good contact between metallic F and S layers made of ordinary metals and standard ferromagnets (see, e.g., recent reviews [6]), the full switching between the superconducting and normal states has been realized only in a few cases [7,8] because ∆T c was usually smaller than the width of the superconducting transition δT c .Very recently, Singh et al. reported [9] the observation of a colossal triplet spin-valve effect for the S/F1/N/F2 structure made of amorphous MoGe, Ni, Cu, and CrO 2 as the S, F1, N, and F2 layers, respectively. This structure demonstrated variation of T c by ∼ 1 K when changing the relative alignment of the two F layers. It was shown that the optimal operational field for this device is of the order of 20 kOe. Gu et al. [10,11] reported ∆T c ∼ 400 mK for Ho/Nb/Ho trilayers. Also in this case the parallel configuration of magnetizations was reached at a field of ∼ 10 kOe. The high operational fields of these spin valves are disadvantageous for the superconducting spintronics. Besides, the physical reasons for large values of ∆T c for spin valve based on half-metals are not yet theoretically explained. This calls for elaboration of classical spinvalve structures which use standard ferromagnets (Fe, Co, Ni) and their alloys with good electrical contacts between all layers and for which theoretical understanding of the operational principle is available.Oh et al. [12] propos...

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

Cited by 99 publications

References 39 publications

Superconducting spin-valve effect and triplet superconductivity inCoOx/Fe1/Cu/Fe2/Cu/Pbmultilayer

Superconducting spin-valve effect and triplet superconductivity inCoOx/Fe1/Cu/Fe2/Cu/Pbmultilayer

Amplitude Control of the Spin-Triplet Supercurrent inS/F/SJosephson Junctions

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

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