The Solitary Superconductivity in Dirty F $$ _1 $$ 1 F $$ _2 $$ 2 S Trilayer with Arbitrary Interfaces

Avdeev, Maxim; Proshin, Yu. N.

doi:10.1007/s10909-016-1661-2

Cited by 8 publications

(5 citation statements)

References 28 publications

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“…[54] (see also Ref. [55]); however, the theoretical formalism was only briefly outlined. Here, we present details of the corresponding derivation.…”

Section: B Structure Typementioning

confidence: 99%

Superconducting spin-valve effect in heterostructures with ferromagnetic Heusler alloy layers

et al. 2019

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We report a comparative analysis and theoretical description of the superconducting properties of two spin-valve-valve structures containing the Heusler alloy Co2Cr1−xFexAly as one of two ferromagnetic (F1 or F2) layers of the F1/F2/S structure, where S stands for the superconducting Pb layer. In our experiments we used the Heusler alloy layer in two roles: as a weak ferromagnet on the place of the F2 layer and as a half-metal on the place of the F1 layer. In the first case, we obtained a large ordinary superconducting spin-valve effect ∆Tc assisted by the triplet superconducting spinvalve effect ∆T trip c . In the second case, we observed a giant magnitude of ∆T trip c reaching 0.5 K. An underlying theory based on the solution of the Usadel equations using Kupriyanov-Lukichev boundary conditions with arbitrary material parameters for all layers and arbitrary boundary parameters for all interfaces is presented in Appendix. We find a good agreement between our experimental data and theoretical results. PACS numbers: 85.75.-d, 74.45+c, 74.25.Nf, 74.78.Fk c − T P c and enclose the operational area of the SSV depicted by the shaded rectangle. Here, T AP c and T P care the SC transition temperatures for AP and P configurations, respectively. At a fixed temperature within this rectangle the change of the mutual orientation of magnetizations from AP to P by an external magnetic field yields a full switching between the SC and the normal state of the SSV. Therefore, the width ∆T f ull c of the shaded area in Fig. 1 is the most important parameter of the SSV. It should be noted, that the commonly used condition for the realization of the full switching effect ∆T c > δT c is, in fact, not sufficient. The actually relevant parameter ∆T f ull c is always smaller than ∆T c due to the finite value of δT c , and this difference gets larger the larger the value of δT c is. In the first experimental realization of the full switching between the normal and SC

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“…[54] (see also Ref. [55]); however, the theoretical formalism was only briefly outlined. Here, we present details of the corresponding derivation.…”

Section: B Structure Typementioning

confidence: 99%

Superconducting spin-valve effect in heterostructures with ferromagnetic Heusler alloy layers

et al. 2019

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“…The two kinds of basic spin valves that have been mainly studied both experimentally and theoretically are F 1 SF 2 and SF 1 F 2 based structures 5,[31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] . These systems offer simple and controllable platforms that can reveal signatures of spin triplet superconducting correlations.…”

Section: Introductionmentioning

confidence: 99%

Half-metallic superconducting triplet spin multivalves

Alidoust

Halterman

2018

Phys. Rev. B

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We study spin switching effects in finite-size superconducting multivalve structures. We examine F 1 F 2 SF 3 and F 1 F 2 SF 3 F 4 hybrids where a singlet superconductor (S) layer is sandwiched among ferromagnet (F) layers with differing thicknesses and magnetization orientations. Our results reveal a considerable number of experimentally viable spin valve configurations that lead to on-off switching of the superconducting state. For S widths on the order of the superconducting coherence length ξ 0 , non-collinear magnetization orientations in adjacent F layers with multiple spin-axes leads to a rich variety of triplet spin-valve effects. Motivated by recent experiments, we focus on samples where magnetizations in the F 1 and F 4 layers exist in a fully spin-polarized half metallic phase, and calculate the superconducting transition temperature, spatially and energy resolved density of states, and the spin-singlet and spin-triplet superconducting correlations. Our findings demonstrate that superconductivity in these devices can be completely switched on or off over a wide range of magnetization misalignment angles due to the generation of equal-spin and opposite-spin triplet pairings.

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“…When constructing devices that consist of superconductor (S) and ferromagnet (F) elements, the F 1 SF 2 and SF 1 F 2 spin valves are some of the simplest configurations with externally controlled system properties. Such platforms have been extensively studied experimentally and theoretically [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In addition to the geometrical properties like the layer thicknesses, the relative magnetization misalignment in these systems plays a pivotal role in determining the end functionality of these systems.…”

Section: Introductionmentioning

confidence: 99%

Supercurrent Diode Effect, Spin Torques, and Robust Zero-Energy Peak in Planar Half-Metallic Trilayers

Halterman,

Alidoust,

Smith

et al. 2021

Preprint

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We consider a Josephson junction with F 1 F 2 F 3 ferromagnetic trilayers in the ballistic regime, where the magnetization in each ferromagnet F i (i = 1, 2, 3), can have arbitrary orientations and magnetization strengths. The trilayers are sandwiched between two s-wave superconductors with a macroscopic phase difference ∆ϕ. With our generalised theoretical and numerical techniques, we are able to study the planar spatial profiles and ∆ϕdependencies of the charge supercurrents, spin supercurrents, spin torques, and density of states for complex systems that are finite in two dimensions. A broad range of magnetization strengths of the central F 2 layer are considered, from an unpolarized normal metal (N) to a half-metallic phase, supporting only one spin species. Our results reveal that when the magnetization configuration in F 1 F 2 F 3 has three orthogonal components, a supercurrent can flow at ∆ϕ = 0, and a strong second harmonic in the current-phase relation appears. Remarkably, upon increasing the magnetization strength in the central ferromagnet layer up to the half-metallic limit, the self-biased current and second harmonic component become dramatically enhanced, and the critical supercurrent reaches its maximum value. The higher harmonics in the current-phase relations can be controlled by the relative magnetization orientations, with negligible current damping compared to the corresponding F 1 N F 3 counterparts. Additionally, for a broad range of exchange field strengths in the central ferromagnet F 2 , the ground state of the system can be tuned to an arbitrary phase difference ϕ 0 , e.g., by rotating the magnetization in the outer ferromagnet F 3 . For intermediate exchange field strengths in F 2 , a ϕ 0 state can arise that creates a superconducting diode effect, whereby ∆ϕ can be tuned to create a one-way dissipationless current flow. The spatial maps of the spin currents and effective magnetic moments reveal a long-ranged spin torque in the halfmetallic phase. Moreover, the density of states studies demonstrate the emergence of zero energy peaks for the mutually orthogonal magnetization configurations, which is strongest in the half-metallic phase. Our results suggest that this simple trilayer Josephson junction can be an excellent candidate for producing experimentally accessible signatures for long-ranged self-biased supercurrents, and supercurrent diode-effects.

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The Solitary Superconductivity in Dirty F $$ _1 $$ 1 F $$ _2 $$ 2 S Trilayer with Arbitrary Interfaces

Cited by 8 publications

References 28 publications

Superconducting spin-valve effect in heterostructures with ferromagnetic Heusler alloy layers

Superconducting spin-valve effect in heterostructures with ferromagnetic Heusler alloy layers

Half-metallic superconducting triplet spin multivalves

Supercurrent Diode Effect, Spin Torques, and Robust Zero-Energy Peak in Planar Half-Metallic Trilayers

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