Gauge theory of the long-range proximity effect and spontaneous currents in superconducting heterostructures with strong ferromagnets

Bobkova, I. V.; Bobkov, A. M.; Силаев, М. А.

doi:10.1103/physrevb.96.094506

Cited by 34 publications

(45 citation statements)

References 58 publications

(148 reference statements)

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“…(6) it is apparent that the current density is nonzero at zero phase difference ϕ = 0 when hr = 0. It is worth mentioning that the appearance of a ϕ0 phase shift in the supercurrent has theoretically been discussed in various situations 13,16,26,27,[62][63][64][65][66][67][68][69][70][71][72] and observed in experiments 73,74 . In structures where the spin orbit meditated coupling is available, its interplay with a properly oriented Zeeman(-like) field results in a supercurrent flow perpendicular to the junction interfaces at zero phase difference 13,16,26,27,71,72 .…”

Section: Methods and Resultsmentioning

confidence: 99%

Spontaneous supercurrent and φ0 phase shift parallel to magnetized topological insulator interfaces

Alidoust

Hamzehpour

2017

Phys. Rev. B

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Employing a Keldysh-Eilenberger technique, we theoretically study the generation of a spontaneous supercurrent and the appearance of the ϕ0 phase shift parallel to uniformly in-plane magnetized superconducting interfaces made of the surface states of a three-dimensional topological insulator. We consider two weakly coupled uniformly magnetized superconducting surfaces where a macroscopic phase difference between the s-wave superconductors can be controlled externally. We find that, depending on the magnetization strength and orientation on each side, a spontaneous supercurrent due to the ϕ0-states flows parallel to the interface at the junction location. Our calculations demonstrate that nonsinusoidal phase relations of current components with opposite directions result in maximal spontaneous supercurrent at phase differences close to π. We also study the Andreev subgap channels at the interface and show that the spin-momentum locking phenomenon in the surface states can be uncovered through density of states studies. We finally discuss realistic experimental implications of our findings.

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Section: Methods and Resultsmentioning

confidence: 99%

Spontaneous supercurrent and φ0 phase shift parallel to magnetized topological insulator interfaces

Alidoust

Hamzehpour

2017

Phys. Rev. B

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“…In this case, it is an equilibrium spin current without dissipation [19]. Although such a spin current is detectable according to Sonin [20], it does not contribute to the transport property in a set up where the spin current can flow in and out.On the other hand, superconducting spintronics is an emerging field attracting recent interest [21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Although the spin degrees of freedom are usually quenched in singlet superconductors, the triplet component can be finite in noncentrosymmetric superconductors, ferromagnet-superconductor hybrids and Josephson junctions, or odd-parity superconductors, where the spins become (partially) active.…”

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confidence: 99%

Spin supercurrent in two-dimensional superconductors with Rashba spin-orbit interaction

Hiroki

Hamamoto

et al. 2019

Commun Phys

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† These authors contribute equally.Spin current is a central theme in spintronics, and its generation is a keen issue. The spin-polarized current injection from the ferromagnet, spin battery, and spin Hall effect have been used to generate spin current, but Ohmic currents in the normal state are involved in all of these methods. On the other hand, the spin and spin current manipulation by the supercurrent in superconductors is a promising route for dissipationless spintronics. Here we show theoretically that, in two-dimensional superconductors with Rashba spin-orbit interaction, the generation of dissipationless bulk spin current by charge supercurrent becomes highly efficient, exceeding that in normal states in the dilute limit, i.e. when the chemical potential is close to the band edge, although the spin density becomes small there. This result manifests the possibility of creating new spintronic devices with long-range coherence.In spintronics, spin current plays an essential role to transfer the information associated with the spin degrees of freedom. Therefore the generation of spin current is an important issue, and several methods have been proposed and experimentally verified [1]. Various methods, such as the spin polarized current injection from the ferromagnet [2-4], spin battery [5-9], and spin Hall effect [10][11][12][13][14][15][16], have been employed to generate the spin current. It has been proposed also that the spin current second order in the electric field can be generated in noncentrosymmetric systems with spin-orbit interaction [17,18]. The spin currents mentioned above are either carried by itinerant electrons through dissipative electric currents, or by localized magnetic moments through exchange interactions. However, there can also be non-dissipative spin current in itinerant-electron systems. In this case, it is an equilibrium spin current without dissipation [19]. Although such a spin current is detectable according to Sonin [20], it does not contribute to the transport property in a set up where the spin current can flow in and out.On the other hand, superconducting spintronics is an emerging field attracting recent interest [21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Although the spin degrees of freedom are usually quenched in singlet superconductors, the triplet component can be finite in noncentrosymmetric superconductors, ferromagnet-superconductor hybrids and Josephson junctions, or odd-parity superconductors, where the spins become (partially) active. Therefore, it is an intriguing issue if one can generate a spin current in superconductors with zero or small dissipation. Actually, the spin supercurrent has been discussed in He3 related to the internal degrees of freedom [39]. Recently, Leurs et al. [40] have reexamined the spin supercurrent in spin-orbit coupled systems, and classified it to the coherent and noncoherent parts, only the latter of which contributes to the continuity equation of the spin density and its gen-eration or manipulation is the focus of sup...

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“…Comparing this equation and Eqs. (62)(63), we see that the signs of the currents δI In the case of the yy-chirality, the coefficients A (y,y) and B (y,y) do not depend on the polarization s. That is, the currents are equal for different spin orientations: δI sp,AP . The analysis of the obtained results shows that the DW reduces the Josephson charge and spin currents if Cooper pairs injected from the right and left superconductors have parallel spin orientation.…”

Section: Change Of the Currents Due To Domain Wallmentioning

confidence: 87%

“…where κ 2 ω = 2|ω|/D F , κ 2 J = 2Jsgn(ω)/D F , J is a exchange field and D F is the diffusion coefficient in the F film which is assumed to be spin-independent. Note that the quasiclassical equations with a spin-dependent D F has been derived previously in various models 62,63 . The 4 × 4 matrix Xik (x) = τi • σk is a tensor product of the Pauli matrices in the Gor'kov-Nambu, τi , and spin space, σk , respectively.…”

Section: Basic Equationsmentioning

confidence: 99%

Charge and Spin Supercurrents in Magnetic Josephson Junctions with Spin Filters and Domain Walls

Dahir,

Volkov,

Eremin

2022

Preprint

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We analyze theoretically the influence of domain walls (DWs) on the DC Josephson current in magnetic superconducting Sm/Fl/F/Fl/Sm junctions. The Josephson junction consists of two "magnetic" superconductors Sm (superconducting film covered by a thin ferromagnetic layer), spin filters Fl and a ferromagnetic layer F with or without DW (DWs). The spin filters Fl allow electrons to pass with one specific spin orientation, such that the Josephson coupling is governed by a fully polarized long-range triplet component. In the absence of DW(s), the Josephson and spin currents are nonzero when the right and left filters, Fl r,l , pass electrons with equal spin orientation and differ only by a temperature-independent factor. They become zero when the spins of the triplet Cooper pairs passing through the Fl r,l have opposite directions. Furthermore, for the different chiralities of the injected triplet Cooper pairs the spontaneous currents arise in the junction yielding a diode effect. Once a DW is introduced, it reduces the critical Josephson current Ic in the case of equal spin polarization and makes it finite in the case of opposite spin orientation. The critical current Ic is maximal when the DW is in the center of the F film. A deviation of the DW from the center generates a force that pushes the DW to the center of the F film. In addition, we consider the case of an arbitrary number N of DW's, with the case N = 2 corresponding to a model system for a magnetic skyrmion.

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Gauge theory of the long-range proximity effect and spontaneous currents in superconducting heterostructures with strong ferromagnets

Cited by 34 publications

References 58 publications

Spontaneous supercurrent and φ0 phase shift parallel to magnetized topological insulator interfaces

Spontaneous supercurrent and φ0 phase shift parallel to magnetized topological insulator interfaces

Spin supercurrent in two-dimensional superconductors with Rashba spin-orbit interaction

Charge and Spin Supercurrents in Magnetic Josephson Junctions with Spin Filters and Domain Walls

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