Nonequilibrium effects in tunnel Josephson junctions

Bezuglyĭ, E. V.; Vasenko, A. S.; Shumeiko, Vitaly; Wendin, Göran

doi:10.1103/physrevb.72.014501

Cited by 34 publications

(30 citation statements)

References 21 publications

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“…It consists of a ferromagnetic layer of thickness d f and two thick superconducting electrodes along the x direction. The left and right superconductor/ferromagnet interfaces are characterized by the dimensionless parameters γ B1 and γ B2 , 32,33 respectively, where γ B1,B2 = R B1,B2 σ n /ξ n , R B1,B2 are the resistances of the left and right S/F interfaces, respectively, σ n is the conductivity of the F layer, ξ n = D f /2πT c , D f is the diffusion coefficient in the ferromagnetic metal, and T c is the critical temperature of the superconductor (we assumeh = k B = 1, except for Sec. V).…”

Section: Model and Basic Equationsmentioning

confidence: 99%

Current-voltage characteristics of tunnel Josephson junctions with a ferromagnetic interlayer

et al. 2011

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We present a quantitative study of the current-voltage characteristics (CVC) of diffusive superconductor/ insulator/ferromagnet/superconductor (SIFS) tunnel Josephson junctions. In order to obtain the CVC we calculate the density of states (DOS) in the F/S bilayer for arbitrary length of the ferromagnetic layer, using quasiclassical theory. For a ferromagnetic layer thickness larger than the characteristic penetration depth of the superconducting condensate into the F layer, we find an analytical expression which agrees with the DOS obtained from a self-consistent numerical method. We discuss general properties of the DOS and its dependence on the parameters of the ferromagnetic layer. In particular we focus our analysis on the DOS oscillations at the Fermi energy. Using the numerically obtained DOS we calculate the corresponding CVC and discuss their properties. Finally, we use CVC to calculate the macroscopic quantum tunneling (MQT) escape rate for the current biased SIFS junctions by taking into account the dissipative correction due to the quasiparticle tunneling. We show that the influence of the quasiparticle dissipation on the macroscopic quantum dynamics of SIFS junctions is small, which is an advantage of SIFS junctions for superconducting qubits applications.

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Section: Model and Basic Equationsmentioning

confidence: 99%

Current-voltage characteristics of tunnel Josephson junctions with a ferromagnetic interlayer

et al. 2011

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“…However, recently Levchenko reported the finding of a dip in the LDOS close to the gap edge for short diffusive Josephson junctions with ideal contacts [26]. Actually, this dip was already seen in former publications [5,[27][28][29][30][31], however, no special attention was paid to it. In a previous work [32] we found the peculiar result that the suppression of the LDOS at is not limited to a dip, but a secondary gap of finite width appears for a diffusive system or chaotic cavity with the normal region connected through ballistic contacts to the superconductors.…”

Section: Introductionmentioning

confidence: 96%

Secondary “smile”-gap in the density of states of a diffusive Josephson junction for a wide range of contact types

et al. 2014

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The superconducting proximity effect leads to strong modifications of the local density of states in diffusive or chaotic cavity Josephson junctions, which displays a phase-dependent energy gap around the Fermi energy. The so-called minigap of the order of the Thouless energy E Th is related to the inverse dwell time in the diffusive region in the limit E Th , where is the superconducting energy gap. In the opposite limit of a large Thouless energy E Th , a small new feature has recently attracted attention, namely, the appearance of a further secondary gap, which is around two orders of magnitude smaller compared to the usual superconducting gap. It appears in a chaotic cavity just below the superconducting gap edge and vanishes for some value of the phase difference between the superconductors. We extend previous theory restricted to a normal cavity connected to two superconductors through ballistic contacts to a wider range of contact types. We show that the existence of the secondary gap is not limited to ballistic contacts, but is a more general property of such systems. Furthermore, we derive a criterion which directly relates the existence of a secondary gap to the presence of small transmission eigenvalues of the contacts. For generic continuous distributions of transmission eigenvalues of the contacts, no secondary gap exists, although we observe a singular behavior of the density of states at . Finally, we provide a simple one-dimensional scattering model which is able to explain the characteristic "smile" shape of the secondary gap.

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“…The analytical solutions can be constructed in the adiabatic limit of small applied voltage eV ≪ ∆ [29]. To make the problem tractable at larger voltages eV ∼ ∆, we make use of the observation that the amplitudes of high-order harmonics of the functionǦ are small in the tunnelling limit W ≪ 1: the amplitude of the mth harmonic decreases with m as W m .…”

Section: Zero-harmonic Modelmentioning

confidence: 99%

Multiparticle tunnelling in diffusive superconducting junctions

Bezuglyĭ¹,

Vasenko²,

Bratus³

et al. 2007

Supercond. Sci. Technol.

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Abstract. We formulate a theoretical framework to describe multiparticle current transport in planar superconducting tunnel junctions with diffusive electrodes. The approach is based on direct solving of quasiclassical Keldysh-Green function equations for nonequilibrium superconductors, and consists of a combination of a circuit theory analysis and improved perturbation expansion. The theory predicts much greater scaling parameter for the subharmonic gap structure of the tunnel current in diffusive junctions compared to the one in ballistic junctions and mesoscopic constrictions with the same barrier transparency.PACS numbers: 74.45.+c, 74.40.+k, 74.25.Fy, 74.50.+r. Multiparticle tunnelling in diffusive superconducting junctions Figure 1. One-dimensional (a) and planar (b) models of the tunnel junction.

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Nonequilibrium effects in tunnel Josephson junctions

Cited by 34 publications

References 21 publications

Current-voltage characteristics of tunnel Josephson junctions with a ferromagnetic interlayer

Current-voltage characteristics of tunnel Josephson junctions with a ferromagnetic interlayer

Secondary “smile”-gap in the density of states of a diffusive Josephson junction for a wide range of contact types

Multiparticle tunnelling in diffusive superconducting junctions

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