Damping Factor of the Riedel Peak in Bridge-Type Josephoson Junctions

Morita, Seizo; Imai, Soichi; Fukushi, I.; Takaki, S.; Takeuti, Yosihisa; Mikoshiba, Nobuo

doi:10.1143/jpsj.52.617

Cited by 9 publications

(4 citation statements)

References 13 publications

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“…In junctions with finite electron transparency D (assumed to be vanishingly small in tunnel junctions), finite D itself directly smears the Riedel singularity [37]. Smearing of any kind turns Riedel singularity into a finite "Riedel peak" of the supercurrent, which was actively studied since the early days of investigations of the Josephson effect -see, e.g., [38][39][40][41][42][43]. These investigations showed that the typical magnitude of the energy gap smearing in tunnel junctions is quite small, on the order of 0.01 of the energy gap itself.…”

Section: Gap Resonance In the Dynamics Of The Current-biased Junctionsmentioning

confidence: 99%

“…( 15) characterizes the gap smearing, and effectively cuts off the current kernels at time t 0 1/(Ωw). As follows from the experimental results [38][39][40][41][42][43], one can use an estimate w 0.01, although the gap smearing strength varies for different junction materials and structures. Such a Gaussian suppression factor for the gap oscillations in time-domain implies that the magnitude of the total energy gap of the junction exhibits small Gaussian fluctuations around the mean value ∆ 1 + ∆ 2 of relative magnitude w. I now discuss the results for the dc current-voltage characteristics ("IV curves") of a current-biased Josephson tunnel junction obtained by the direct numerical solution of the integro-differential equations (10) with the current kernels (11) regularized according to Eq.…”

Section: Gap Resonance In the Dynamics Of The Current-biased Junctionsmentioning

confidence: 99%

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Gap resonance in the classical dynamics of the current-biased Josephson tunnel junctions

Averin

2021

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This work reports a novel time-domain expression for the current-response kernels of a Josephson tunnel junction between BCS superconductors with in general different energy gaps, and its use to simulate the classical dynamics of such junctions. The simulations show a dynamic regime characterized by the resonance between the Josephson oscillations and the gap oscillations in the asymptotics of the current kernels that has not been studied previously. The resonance manifests itself as a hysteresis in the dc current-voltage characteristics of the current-biased junctions in the voltage range above the energy gap, in addition to the usual "inertial" hysteresis characteristic for tunnel junctions at voltages below the energy gap. Features of the IV curves related to the gap resonance, including the above-the-gap hysteresis, should manifest themselves in many structures and devices utilizing high-quality Josephson tunnel junctions with relatively large, but achievable current densities.

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Section: Gap Resonance In the Dynamics Of The Current-biased Junctionsmentioning

confidence: 99%

Section: Gap Resonance In the Dynamics Of The Current-biased Junctionsmentioning

confidence: 99%

Gap resonance in the classical dynamics of the current-biased Josephson tunnel junctions

Averin

2021

Preprint

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“…As a function of applied voltage, V, the amplitudes, I c1 and I c2 , show singularities originating from the gap, Á, in an s-wave superconductor. The I c1 has a logarithmic divergence called the Riedel peak at the gap voltage, V ¼ 2Á=e, due to the square root singularities in the density of states, [2][3][4][5][6][7] while the I c2 shows a discontinuity at V ¼ 2Á=e and is zero below V < 2Á=e at zero temperature. 3,5) The I c2 is experimentally observed near the superconducting transition temperature, T c , 8) in various types of Josephson junctions.…”

Section: Introductionmentioning

confidence: 99%

Sign Reversal of AC Josephson Current in a Ferromagnetic Josephson Junction

et al. 2009

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The ac Josephson effect in a ferromagnetic Josephson junction, which is composed of two superconductors separated by a ferromagnetic metal (FM), is studied by a tunneling Hamiltonian and Green's function method. We obtain two types of superconducting phase dependent currents, i.e., Josephson current and quasiparticle-pair-interference current (QPIC). These currents change their signs with thickness of the FM layer due to the 0-transition characteristic to the ferromagnetic Josephson junction. As a function of applied voltage, the Josephson critical current shows a logarithmic divergence called the Riedel peak at the gap voltage, while the QPIC shows a discontinuous jump. The Riedel peak reverses due to the 0-transition and disappears near the 0-transition point. The discontinuous jump in the QPIC also represents similar behaviors to the Riedel peak. These results are in contrast to the conventional ones.

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“…The I c2 is experimentally observed near the superconducting transition temperature, T c [6]. The ac Josephson effect has been studied in various types of Josephson junctions [7,8]. For instance, in a Josephson junction where two superconductors are separated by a small normal metal (NM), it is found that the above mentioned singularities with V are suppressed when the interfaces are highly transparent [8].…”

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confidence: 99%