Josephson effect in S/F/S junctions: Spin bandwidth asymmetry versus Stoner exchange

Annunziata, Gaetano; Enoksen, Henrik; Linder, Jacob; Cuoco, Mario; Noce, Canio; Sudbø, Asle

doi:10.1103/physrevb.83.144520

Cited by 35 publications

(35 citation statements)

References 63 publications

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“…We can easily see than the period of Andreev level is 4π, which obeys the generate relation ε AR ∝ cos(φ/2) [21], while the period of ε AR /∆ s is 2π as shown in Fig.4, which is consistent with the results of Ref. [10]. We detect the effects of the electric field, off-resonance circularly polarized light, chemical potential, and length of the normal region to the Andreev bound level numerically.…”

Section: Resultssupporting

confidence: 89%

“…The reversal of the Josephson effect will be rised by the valley, spin, and pseudospin polarization, which with dramatic dipole oscillation between the two components induced by the off-resonance circularly polarized light as we have discussed [8], and results in a nonzero centerof-mass (COM) wave vector, just like the Josephson current realized by a ferromagnetic middle silicene (in superconductor/ferromagnet/superconductor ballistic Josephson junction [10]). It's found that the oscillation of valley polarization is related to the carrier-phonon scattering due to the photoexcitation which has a relaxation time in picosecond range [17] (since the frequency of light is setted in the terahertz range) and larger than that of the electron-eletron scattering.…”

Section: Andreev Bound Statementioning

confidence: 99%

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Electric Field and Light Field Modulated Josephson Effect in Silicene-Based SNS Josephson Junction: Andreev Reflection and Free Energy

2019

Silicon

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We investigate the Josephson effcet in superconductor-normal-superconductor junction (SNS) base on the doped unbiased silicene under the perpendicular electric field and off-resonance circularly polarized light. The Andreev reflection (including the retroreflection and specular one) during the subgap transport, the free energy, and the reversal of the Josephson effect as well as the emergence of φ 0 -junction are exploited. The Andreev reflection is complete in the NS interface even for the clean interface and without the Fermi wave vector mismatch, which is opposite to the case of ferromagnet-superconductor interface. The important role played by the dynamical polarization of the degrees of freedom to the 0 − π transition and the generation of φ 0 -junction are mentioned in this paper. The scattering by the charged impurity in the substrate affects the transport properties in the bulk as well as the valley relaxation, which can be taken into consider by the macroscopic wave function. In short junction limit, the approximated results about the Andreev level and free energy are also discussed. Beside the low-energy limit of the tight-binding model, the finite-size effect need to be taken into account as long as the spacing model is much larger than the superconducting gap. D − U) 2 / v F with U the electrostatic potential induced by the doping or gate voltage in the superconducting region, which breaks the electron-hole symmetry, and lifts the zero-model (between the lowest conduction band and the highest valence band) above the Fermi level (imaging the zero Dirac-mass here) [1]. The U has been experimentally proved to be valid in controlling the phase shift of the φ 0 -junction as well as the 0 − π transition[2] like the bias voltage. Note that the Dirac-mass here is related to the band gap by ∆ = 2m ησz τz D . Thus we can know that µ s (m ησz τz D − U) 2 and the incident angle is larger than the transmission *

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Section: Resultssupporting

confidence: 89%

Section: Andreev Bound Statementioning

confidence: 99%

Electric Field and Light Field Modulated Josephson Effect in Silicene-Based SNS Josephson Junction: Andreev Reflection and Free Energy

2019

Silicon

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“…The consequences of this have been addressed in the context of superconductor-ferromagnet proximity effect. 74 Although the barrier is spin-orbit coupled, this coupling will not lead to any spin Hall effects at the boundaries z = 0 and z = −a. Consequently, there is no accumulation of spin and the basic ballistic boundary conditions are identical to those in the theory of a conventional tunnel junction, namely:…”

Section: A Equations Of Motionmentioning

confidence: 99%

Microscopic theory for a ferromagnetic nanowire/superconductor heterostructure: Transport, fluctuations, and topological superconductivity

Takei

Galitski

2012

Phys. Rev. B

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Motivated by the recent experiment of Wang et al. [Nature Physics 6, 389 (2010)], who observed a highly unusual transport behavior of ferromagnetic Cobalt nanowires proximity-coupled to superconducting electrodes, we study proximity effect and temperature-dependent transport in such a mesoscopic hybrid structure. It is assumed that the asymmetry in the tunneling barrier gives rise to the Rashba spin-orbit-coupling in the barrier that enables induced p-wave superconductivity in the ferromagnet to exist. We first develop a microscopic theory of Andreev scattering at the spin-orbit-coupled interface, derive a set of self-consistent boundary conditions, and find an expression for the p-wave mini-gap in terms of the microscopic parameters of the contact. Second, we study temperature-dependence of the resistance near the superconducting transition and find that it should generally feature a fluctuation-induced peak. The upturn in resistance is related to the suppression of the singleparticle density of states due to the formation of fluctuating pairs, whose tunneling is suppressed. In conclusion, we discuss this and related setups involving ferromagnetic nanowires in the context of one-dimensional topological superconductors. It is argued that to realize unpaired end Majorana modes, one does not necessarily need a half-metallic state, but a partial spin polarization may suffice. Finally, we propose yet another related class of material systems -ferromagnetic semiconductor wires coupled to ferromagnetic superconductors -where direct realization of Kitaev-Majorana model should be especially straightforward.

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“…On solving the boundary conditions, we have 8 Andreev bound states given as E i (i = 1, ..., 8) = ±ε p (p = 1, ..., 4). From Andreev bound states energies [27] we get the Free energy of our system, which is given by [18]:…”

Section: Josephson Charge Currentmentioning

confidence: 99%

Spin-flip scattering engendered quantum spin torque in a Josephson junction

Pal

Benjamin

2019

Proc. R. Soc. A.

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We examine a Josephson junction with two ferromagnet's and a magnetic impurity sandwiched between two superconductors. In such ferromagnetic Josephson junctions equilibrium spin torque exists only when ferromagnet's are misaligned. This is explained via the "conventional" mechanism of spin transfer torque, which owes its origin to the misalignment of two ferromagnet's. However, we see surprisingly when the magnetic moments of the ferromagnet's are aligned parallel or anti-parallel, there is a finite equilibrium spin torque due to the quantum mechanism of spin flip scattering. We explore the properties of this unique spin flip scattering induced equilibrium quantum spin torque, especially its tunability via exchange coupling and phase difference across the superconductors.

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Josephson effect in S/F/S junctions: Spin bandwidth asymmetry versus Stoner exchange

Cited by 35 publications

References 63 publications

Electric Field and Light Field Modulated Josephson Effect in Silicene-Based SNS Josephson Junction: Andreev Reflection and Free Energy

Electric Field and Light Field Modulated Josephson Effect in Silicene-Based SNS Josephson Junction: Andreev Reflection and Free Energy

Microscopic theory for a ferromagnetic nanowire/superconductor heterostructure: Transport, fluctuations, and topological superconductivity

Spin-flip scattering engendered quantum spin torque in a Josephson junction

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