Chirality and spin transformation of triplet Cooper pairs upon interaction with singlet condensate

Moor, Andreas; Volkov, A. N.; Efetov, K. B.

doi:10.1103/physrevb.92.214510

Cited by 28 publications

(42 citation statements)

References 107 publications

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“…The spontaneous phase shift of Josephson current has been obtained in several FM/SC systems [25,27,30,35,[41][42][43][44][45][46][47][48][49][50][51][52][53][54]]. Here we demonstrate that this effect is essential only for the case of strong ferromagnets.…”

Section: Spontaneous Josephson Current Through Strong Ferromagnetssupporting

confidence: 54%

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

2017

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Gauge theory of the long-range proximity effect and spontaneous currents in superconducting heterostructures with strong ferromagnets Bobkova, I. V.; Silaev, Mikhail Bobkova, I. V., Bobkov, A. M., & Silaev, M. (2017). Gauge theory of the long-range proximity effect and spontaneous currents in superconducting heterostructures with strong ferromagnets. Physical Review B, 96 (9) We present the generalized quasiclassical theory of the long-range superconducting proximity effect in heterostructures with strong ferromagnets, where the exchange splitting is of the order of Fermi energy. In the ferromagnet the propagation of equal-spin Cooper pairs residing on the spin-split Fermi surfaces is shown to be governed by the spin-dependent Abelian gauge field which results either from the spin-orbital coupling or from the magnetic texture. This additional gauge field enters into the quasiclassical equations in superposition with the usual electromagnetic vector potential and results in the generation of spontaneous superconducting currents and phase shifts in various geometries which provide the sources of long-range spin-triplet correlations. We derive the Usadel equations and boundary conditions for the strong ferromagnet and consider several generic examples of the Josephson systems supporting spontaneous currents.

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Section: Spontaneous Josephson Current Through Strong Ferromagnetssupporting

confidence: 54%

“…The spin-gauge field Z x = 0 and finite spin splitting D + = D − in the CPR (50) lead to the spontaneous current at zero phase difference known as the anomalous Josephson effect. The ground-state phase difference χ 0 can be found from the zero-current condition I (χ = χ 0 ) = 0:…”

Section: Spontaneous Josephson Current Through Strong Ferromagnetsmentioning

confidence: 99%

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

2017

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“…Studies, based on quasiclassics, of the diffusive Josephson junctions through various noncoplanar structures, including a helix [40], magnetic vortex [41], and skyrmion [42], have shown no AJE. In contrast, in diffusive systems with half-metallic elements [29,31] and in junctions between magnetic superconductors with spin filters [35,36] a finite anomalous current has been predicted. From this apparent contradiction, the general condition for the AJE in diffusive systems still remains elusive.…”

Section: Introductionmentioning

confidence: 95%

Anomalous current in diffusive ferromagnetic Josephson junctions

2017

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We demonstrate that in diffusive superconductor/ferromagnet/superconductor (S/F/S) junctions a finite, anomalous Josephson current can flow even at zero phase difference between the S electrodes. The conditions for the observation of this effect are noncoplanar magnetization distribution and a broken magnetization inversion symmetry of the superconducting current. The latter symmetry is intrinsic for the widely used quasiclassical approximation and prevented previous works based on this approximation from obtaining the Josephson anomalous current. We show that this symmetry can be removed by introducing spin-dependent boundary conditions for the quasiclassical equations at the superconducting/ferromagnet interfaces in diffusive systems. Using this recipe, we consider generic multilayer magnetic systems and determine the ideal experimental conditions in order to maximize the anomalous current.

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“…[17][18][19][20] and references therein) or complicated noncollinear distribution of the magnetization (see Refs. [21][22][23] and references therein).…”

Section: Introductionmentioning

confidence: 99%

Anomalous Josephson effect controlled by an Abrikosov vortex

et al. 2017

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The possibility of a fast and precise Abrikosov vortex manipulation by a focused laser beam opens the way to create laser-driven Josephson junctions. We theoretically demonstrate that a vortex pinned in the vicinity of the Josephson junction generates an arbitrary ground state phase which can be equal not only to 0 or π but to any desired ϕ 0 value in between. Such ϕ 0 junctions have many peculiar properties and may be effectively controlled by the optically driven Abrikosov vortex. Also we theoretically show that the Josephson junction with the embedded vortex can serve as an ultrafast memory cell operating at sub THz frequencies. I. INTRODUCTIONJosephson junctions (JJs) with nonzero spontaneous phase difference between the superconducting electrodes in the ground state (the so-called π , ϕ 0 , and ϕ JJs) have become the subject of intensive theoretical and experimental study during the past decade [1,2]. The most striking feature of such junctions is their ability to generate a current in the superconducting circuit, thus acting as a phase battery [3][4][5][6]. In addition, relatively small variation of the system parameters may provoke dramatic changes in the ground state phase difference, which is believed to provide new effective tools for controlling the currents in microelectronic devices (see, e.g., Refs. [7,8]).There are several generic mechanisms leading to the spontaneous appearance of nonzero Josephson phase. The basic one reveals when the superconducting (S) electrodes are separated by a ferromagnetic (F) layer. The exchange field inside the ferromagnet produces the spatial oscillations of the Cooper pair wave function, and depending on the ratio between the oscillation period and the F-layer thickness the ground state phase is equal to 0 or π (these cases are referred as 0 or π JJs, respectively) [9][10][11]. A peculiar situation is realized when the thickness d of the ferromagnet varies along the junction in a way that in some parts of the ferromagnet the value of d corresponds to the 0 state while in other parts to the π state (see Ref. [12] and references therein). If there is only a slight difference between the areas of the "0" and "π " regions the phase frustration can result in the appearance of a state with the spontaneous phase difference φ = ±ϕ = 0,π which is degenerate (ϕ JJ) (see Ref.[13] and references therein). A similar effect takes place in Josephson junctions with the current injectors acting as an effective source of the phase jumps along the junction (see and references therein). One can also obtain a ϕ 0 JJ, where the ground state phase φ = ϕ 0 is not degenerate, e.g., using the JJs with broken inversion symmetry [17]. In this case the superconducting current I through the junction should not be necessarily an odd function of the phase difference φ and can take the form I = I c sin(φ + ϕ 0 ) [17]. Such situation is realized in the S|F|S junctions with strong spin-orbit coupling (see and references therein) or complicated noncollinear distribution of the magnetization (see an...

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Chirality and spin transformation of triplet Cooper pairs upon interaction with singlet condensate

Cited by 28 publications

References 107 publications

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

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

Anomalous current in diffusive ferromagnetic Josephson junctions

Anomalous Josephson effect controlled by an Abrikosov vortex

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