Basic Superconducting Spin Valves

Kushnir, V. N.; Сидоренко, А. С.; Тагиров, Л. Р.; Kupriyanov, M. Yu.

doi:10.1007/978-3-319-90481-8_1

Cited by 8 publications

(5 citation statements)

References 142 publications

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“…The exchange bias (EB) effect arises on the interface of antiferromagnetic (AF) and ferromagnetic (F) magnetic phases and leads to the shift of the hysteresis loop on value of H eb varying from several Oersteds to kOe (see review [1]). The effect was discovered 60 years ago, wellstudied to the date [1,2] and is utilized in creation of spin-valves including superconducting devices [3][4][5][6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Chirality of Bloch domain walls in exchange biased CoO/Co bilayer seen by waveguide-enhanced neutron spin-flip scattering

Khaydukov,

Lenk,

Zdravkov

et al. 2021

Preprint

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Magnetic state of exchanged biased CoO(20nm)/Co(dF ) bilayer (dF =5-20nm) was studied by means of polarized neutron reflectometry. By spacing of CoO/Co bilayer and Al2O3 substrate with Nb(20nm) layer we created waveguide structure which allowed us to significantly enhance intensity of spin-flip (SF) scattering in the position of optical resonances. For the trained sample with thinnest Co(5nm) we detected strong SF scattering at the resonance position (up to 30% of incoming intensity) speaking about high non-collinearity of the system. As dF increases, the intensity of SF scattering linearly decreases. At the same time we observed asymmetry of up-down and down-up scattering channels at the resonance positions. We attribute this asymmetry to the Zeeman splitting of neutrons energies with different initial polarization taking place in high external field. Analysis, however, shows that the applied in the PNR experiment external field is not enough to quantitatively explain the observed asymmetry for the samples with dF > 5nm and we have to postulate presence of additional magnetic field produced by sample. We attribute this additional field to the stray field produced by chiral Bloch domain walls. The chirality of the domain walls can be explained by Dzyaloshinskii-Moriya interaction arising at the CoO/Co interface. Our results can be useful for designing of spintronic devices using exchange bias effect.

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Section: Introductionmentioning

confidence: 99%

Chirality of Bloch domain walls in exchange biased CoO/Co bilayer seen by waveguide-enhanced neutron spin-flip scattering

Khaydukov,

Lenk,

Zdravkov

et al. 2021

Preprint

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“…Magnetoresistance measurements demonstrate that the structure exhibits superconducting spin-valve effect. The underlying phenomena behind the magnetic Josephson junctions and superconducting spin-valves are the superconductor–ferromagnet proximity effects [ 51 , 52 , 53 ].…”

Section: Introductionmentioning

confidence: 99%

“…This, in turn, affects the interference of the superconducting pairing wave functions in the layers, and it becomes possible to control the superconductivity in a heterostructure by manipulating the magnetic configurations. Such structures are called superconducting spin-valves (see reviews [ 51 , 52 ] and citations therein).…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Magnetoresistive Properties of the Epitaxial Pd0.96Fe0.04/VN/Pd0.92Fe0.08 Superconducting Spin-Valve Heterostructure

et al. 2020

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A thin-film superconductor(S)/ferromagnet(F) F1/S/F2-type Pd0.96Fe0.04(20 nm)/VN(30 nm)/Pd0.92Fe0.08(12 nm) heteroepitaxial structure was synthesized on (001)-oriented single-crystal MgO substrate utilizing a combination of the reactive magnetron sputtering and the molecular-beam epitaxy techniques in ultrahigh vacuum conditions. The reference VN film, Pd0.96Fe0.04/VN, and VN/Pd0.92Fe0.08 bilayers were grown in one run with the target sample. In-situ low-energy electron diffraction and ex-situ X-ray diffraction investigations approved that all the Pd1−xFex and VN layers in the series grew epitaxial in a cube-on-cube mode. Electric resistance measurements demonstrated sharp transitions to the superconducting state with the critical temperature reducing gradually from 7.7 to 5.4 K in the sequence of the VN film, Pd0.96Fe0.04/VN, VN/Pd0.92Fe0.08, and Pd0.96Fe0.04/VN/Pd0.92Fe0.08 heterostructures due to the superconductor/ferromagnet proximity effect. Transition width increased in the same sequence from 21 to 40 mK. Magnetoresistance studies of the trilayer Pd0.96Fe0.04/VN/Pd0.92Fe0.08 sample revealed a superconducting spin-valve effect upon switching between the parallel and antiparallel magnetic configurations, and anomalies associated with the magnetic moment reversals of the ferromagnetic Pd0.92Fe0.08 and Pd0.96Fe0.04 alloy layers. The moderate critical temperature suppression and manifestations of superconducting spin-valve properties make this kind of material promising for superconducting spintronics applications.

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“…Also, critical current of JJs with magnetic barriers (magnetic JJs) can be varied by changing their internal magnetization. This feature can be used in cryogenic memories, superconducting spintronics, and other applications, see [13], [22], [23] for a review. However, an industrial quality technology for integration of magnetic π-junctions with regular (0shift) junctions in large-scale integrated circuits has not been developed, despite a considerable amount of research on Josephson junctions with a vast variety of magnetic barriers, and demonstrations of simple circuits.…”

Section: Introductionmentioning

confidence: 99%

Planarized Fabrication Process With Two Layers of SIS Josephson Junctions and Integration of SIS and SFS <italic>π</italic>-Junctions

Tolpygo

Bolkhovsky

Rastogi

et al. 2019

IEEE Trans. Appl. Supercond.

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We present our new fabrication Process for Superconductor Electronics (PSE2) that integrates two (2) layers of Josephson junctions (JJs) in a fully planarized multilayer process on 200-mm wafers. The two junction layers can be, e.g., conventional Superconductor-Insulator-Superconductor (SIS) Nb/Al/AlOx/Nb junctions with the same or different Josephson critical current densities, Jc. The process also allows integration of high-Jc Superconductor-Ferromagnet-Superconductor (SFS) or SFS'S JJs on the first junction layer with Nb/Al/AlOx/Nb trilayer junctions on the second JJ layer, or vice versa. In the present node, the SFS trilayer, Nb/Ni/Nb is placed below the standard SIS trilayer and separated by one niobium wiring layer. The main purpose of integrating the SFS and SIS junction layers is to provide compact π-phase shifters in logic cells of superconductor digital circuits and random access memories, and thereby increase the integration scale and functional density of superconductor electronics. The current node of the two-junction-layer process has six planarized niobium layers, two layers of resistors, and 350-nm minimum feature size. The target critical current densities for the SIS JJs are 100 μA/μm 2 and 200 μA/μm 2 . We present the salient features of the new process, fabrication details, and characterization results on two layers of JJs integrated into one process, both for the conventional and πjunctions.

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Basic Superconducting Spin Valves

Cited by 8 publications

References 142 publications

Chirality of Bloch domain walls in exchange biased CoO/Co bilayer seen by waveguide-enhanced neutron spin-flip scattering

Chirality of Bloch domain walls in exchange biased CoO/Co bilayer seen by waveguide-enhanced neutron spin-flip scattering

Synthesis, Characterization, and Magnetoresistive Properties of the Epitaxial Pd0.96Fe0.04/VN/Pd0.92Fe0.08 Superconducting Spin-Valve Heterostructure

Planarized Fabrication Process With Two Layers of SIS Josephson Junctions and Integration of SIS and SFS <italic>π</italic>-Junctions

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