Effects of anharmonicity of current-phase relation in Josephson junctions (Review Article)

Askerzade, I. N.

doi:10.1063/1.4916071

Cited by 20 publications

(11 citation statements)

References 72 publications

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“…As discussed, at low temperatures the CΦR of the SNS junctions is expected to become considerably skewed. In this case it is expected that fractional Shapiro steps can appear due to phase locking between the incident RF radiation and a higher harmonic of the CΦR [17][18][19] . Figure 5a (negative field values), shows the experimentally obtained field dependence of the Shapiro response for the anisotropic JJA (Device 2) at T = 0.4 K. Some clear differences can be observed with the map at T = 1.8 K (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In case the weak link is characterized by a conventional sinusoidal current-phase relationship, this resonant response manifests itself as constant voltage plateaus, so called Shapiro steps, in the voltage versus current (VI)-characteristics of the junction at voltages V n = nΦ 0 ν rf , where n 2 Z and Φ 0 the fluxquantum 16 . However, for a weak link having a 2π periodic non-sinusoidal CΦR, the response exhibits, in addition to the conventional integer Shapiro steps, steps at fractional values V n/q = (n/q)Φ 0 ν rf , where the qth (q ≠ n) fractional step originates from the phase-locked response with the qth harmonic of the CΦR [17][18][19] . Similarly, the 4π periodicity of the Majorana bound state spectrum in topological Josephson junctions, is expected to leave a fingerprint in the Shapiro step response 10 .…”

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confidence: 99%

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Giant fractional Shapiro steps in anisotropic Josephson junction arrays

et al. 2020

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Giant fractional Shapiro steps have been observed in Josephson junction arrays as resulting from magnetic flux quantization in the two-dimensional array. We demonstrate experimentally the appearance of giant fractional Shapiro steps in anisotropic Josephson junction arrays as unambiguous evidence of a skewed current phase relationship. Introducing anisotropy in the array results in a giant collective high frequency response that reflects the properties of a single junction, as evidenced by the observation of a Fraunhofer like magnetic field dependence of the total critical current of the system. The observed phase dynamics can be perfectly captured within an extended resistively shunted Josephson junction model. These results directly indicate the potential of Josephson junction arrays to explore the current phase relation in a very broad frequency range (down to 50 MHz) and in a wide variety of novel link materials exhibiting non-conventional current phase relationships.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Giant fractional Shapiro steps in anisotropic Josephson junction arrays

et al. 2020

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“…Here we study the resistively and capacitatively shunted array model (RCSJ) of the small SFS or SIFS junctions where the intercell inductance is taken into account. According to [10,11] for such junctions one should consider not only the first harmonic of the current-phase relation, but also the second one: I s (φ) = I c sin φ + I (2) c sin 2φ. In the RCSJ model the equations of motion of the JJA are derived from the combined Josephson relations, the Kirchhoff law and the flux quantization rules [15,37].…”

Section: The Model and Equations Of Motionmentioning

confidence: 99%

“…It is used to describe the dynamics of long Josephson junctions (JJs) of the superconducotor-ferromagnet-superconducotor (SFS) and/or superconducotor-insulator-ferromagnetsuperconducotor (SIFS) type [8,9]. In these junctions the current-phase relation differs significantly from the single-harmonic dependence and the second harmonic is taken into account [10,11]. Also the non-local generalization of the DbSG has been used to describe the long JJ where the superconducting layers are thin [12].…”

Section: Introductionmentioning

confidence: 99%

Embedded solitons in the double sine-Gordon lattice with next-neighbor interactions

Zolotaryuk

Starodub

2019

Phys. Rev. E

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Topological solitons can propagate without radiation in discrete media. These solutions are known as embedded solitons (ES). They come as isolated solutions and exist despite their resonance with the linear spectrum of the respective lattices. In this paper the properties of embedded solitons in the discrete double sine-Gordon equation with the next-neighbor and second-neighbor interactions are investigated. Depending on the sign of these interactions they can be either destructive or favorable for the ES creation. The ES existence area depends on the width of the linear spectrum: narrowing of the spectrum widens the ES existence range and vice versa. The application to the Josephson junction arrays is discussed.

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“…These voltages depend only on a fundamental constant, the flux quantum 0 , and the driving frequency ν ac . Further, q ∈ N 0 , n ∈ Z, and the qth ( = n) fractional step originates from the phase-locked response with the qth harmonic in the current-phase relation (C R) [3][4][5],…”

Section: Introductionmentioning

confidence: 99%

Fractional Shapiro steps in resistively shunted Josephson junctions as a fingerprint of a skewed current-phase relationship

et al. 2020

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We study numerically the fractional Shapiro step response in low-frequency driven Josephson junctions which have a nonsinusoidal current-phase relation. We perform this study within the resistively shunted Josephson junction model. We demonstrate that fractional steps, as a fingerprint of a skewed current phase relation, will manifest themselves only for higher values of the reduced frequency. We compare the theoretical observations with experimental measurements in an anisotropic Josephson junction array containing over 500 superconductornormal-superconductor junctions having a skewed current phase relation. We demonstrate that changing the critical current by applying a magnetic field is a robust method to modify the reduced frequency over a broad range of values. The presence of fractional Shapiro steps at high values of the reduced frequency directly confirm the theoretical results.

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Effects of anharmonicity of current-phase relation in Josephson junctions (Review Article)

Cited by 20 publications

References 72 publications

Giant fractional Shapiro steps in anisotropic Josephson junction arrays

Giant fractional Shapiro steps in anisotropic Josephson junction arrays

Embedded solitons in the double sine-Gordon lattice with next-neighbor interactions

Fractional Shapiro steps in resistively shunted Josephson junctions as a fingerprint of a skewed current-phase relationship

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