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Valerij A. Shklovskij - One of the best experts on this subject based on the ideXlab platform.
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DC to AC converter on Abrikosov vortices in a washboard Pinning Potential
Journal of Physics: Conference Series, 2014Co-Authors: Valerij A. Shklovskij, Oleksandr V. DobrovolskiyAbstract:The nonlinear dynamics of Abrikosov vortices in a cosine dc-biased washboard Pinning Potential at nonzero temperature is theoretically investigated. The problem is treated relying upon the exact solution of the Langevin equation for non-interacting vortices by using the Fokker-Planck method combined with the scalar continued fractions technique. The time variation of the local mean vortex velocity v(t) is calculated. The time voltage E(t) ? v(t) is predicted to oscillate with a dc current-dependent frequency and a tunable pulse shape. Formulas for v(t) are discussed as functions of dc transport current and temperature, in a wide range of the corresponding dimensionless parameters. The derived expressions can be adapted for a number of physical applications utilizing the overdamped motion of a Brownian particle in a tilted cosine Potential, e.g., the resistively shunted Josephson junction model.
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Stochastic resonance of vortices in a washboard Pinning Potential
Physica C: Superconductivity and its Applications, 2014Co-Authors: Valerij A. Shklovskij, Oleksandr V. DobrovolskiyAbstract:Abstract In a bistable Potential at low temperatures, stochastic resonance can be characterized as a synchronization effect of the hopping mechanism induced by an external periodic stimulus, where synchronization attains a maximum by fine-tuning the forcing frequency close to the relevant switching rate. In this work, we theoretically investigate the nonlinear single-vortex dynamics in a tilted cosine (multistable) washboard Pinning Potential at nonzero temperature in the presence of dc and ac currents of arbitrary amplitudes and frequency. The conditions for stochastic resonance to appear are derived on the basis of the exact solution of the corresponding Langevin equation for non-interacting vortices in terms of a matrix continued fraction. The nonlinear ac voltage response is analyzed as a function of temperature, dc bias, ac amplitude and frequency, with particular focus on the amplification of the external harmonic signal and its conversion to the third harmonics of the input frequency.
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vortex ratchet reversal in an asymmetric washboard Pinning Potential subject to combined dc and ac stimuli
arXiv: Superconductivity, 2013Co-Authors: Valerij A. Shklovskij, Oleksandr V. Dobrovolskiy, Vladimir V. SosedkinAbstract:The mixed-state resistive response of a superconductor thin film with an asymmetric washboard Pinning Potential subject to superimposed dc and ac currents of arbitrary amplitudes and frequency at finite temperature is theoretically investigated. The problem is considered in the single-vortex approximation, relying upon the exact solution of the Langevin equation in terms of a matrix continued fraction. The dc voltage response and the absorbed power in ac response are analyzed as functions of dc bias, ac current amplitude and frequency, in a wide range of corresponding dimensionless parameters. Predictions are made of (i) a reversal of the rectified voltage at small dc biases and strong ac drives and (ii) a non-monotonic enhancement of the absorbed power in the nonlinear ac response at far sub-dePinning frequencies. It is elucidated how and why both these effects appear due to the competition of the fixed internal and the tunable, dc bias-induced external asymmetry of the Potential as the only reason. This is distinct from other scenarios used for explaining the vortex ratchet reversal effect so far.
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determination of coordinate dependence of a Pinning Potential from a microwave experiment with vortices
Low Temperature Physics, 2013Co-Authors: Valerij A. Shklovskij, Oleksandr V. DobrovolskiyAbstract:The measurement of the complex impedance response accompanied by power absorption P(ω) in the radiofrequency and microwave ranges represents a most popular experimental method for the investigation of Pinning mechanisms and vortex dynamics in type-II superconductors. In the theory, the Pinning Potential (PP) well for a vortex must be a priori specified in order to subsequently analyze the measured data. We have theoretically solved the inverse problem at T = 0 K and exemplify how the coordinate dependence of a PP can be determined from a set of experimental curves P(ω|j0) measured at subcritical dc currents 0 < j0 < jc under a small microwave excitation j1 ≪ jc with frequency ω. We furthermore elucidate how and why the dePinning frequency ωp, which separates the non-dissipative (quasi-adiabatic) and the dissipative (high-frequency) regimes of small vortex oscillations in the PP, is reduced with increasing j0. The results can be directly applied to a wide range of conventional superconductors with a PP sub...
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Determination of coordinate dependence of a Pinning Potential from a microwave experiment with vortices
Low Temperature Physics, 2013Co-Authors: Valerij A. Shklovskij, Oleksandr V. DobrovolskiyAbstract:The measurement of the complex impedance response accompanied by power absorption P(ω) in the radiofrequency and microwave ranges represents a most popular experimental method for the investigation of Pinning mechanisms and vortex dynamics in type-II superconductors. In the theory, the Pinning Potential (PP) well for a vortex must be a priori specified in order to subsequently analyze the measured data. We have theoretically solved the inverse problem at T = 0 K and exemplify how the coordinate dependence of a PP can be determined from a set of experimental curves P(ω|j0) measured at subcritical dc currents 0
Oleksandr V. Dobrovolskiy - One of the best experts on this subject based on the ideXlab platform.
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DC to AC converter on Abrikosov vortices in a washboard Pinning Potential
Journal of Physics: Conference Series, 2014Co-Authors: Valerij A. Shklovskij, Oleksandr V. DobrovolskiyAbstract:The nonlinear dynamics of Abrikosov vortices in a cosine dc-biased washboard Pinning Potential at nonzero temperature is theoretically investigated. The problem is treated relying upon the exact solution of the Langevin equation for non-interacting vortices by using the Fokker-Planck method combined with the scalar continued fractions technique. The time variation of the local mean vortex velocity v(t) is calculated. The time voltage E(t) ? v(t) is predicted to oscillate with a dc current-dependent frequency and a tunable pulse shape. Formulas for v(t) are discussed as functions of dc transport current and temperature, in a wide range of the corresponding dimensionless parameters. The derived expressions can be adapted for a number of physical applications utilizing the overdamped motion of a Brownian particle in a tilted cosine Potential, e.g., the resistively shunted Josephson junction model.
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Stochastic resonance of vortices in a washboard Pinning Potential
Physica C: Superconductivity and its Applications, 2014Co-Authors: Valerij A. Shklovskij, Oleksandr V. DobrovolskiyAbstract:Abstract In a bistable Potential at low temperatures, stochastic resonance can be characterized as a synchronization effect of the hopping mechanism induced by an external periodic stimulus, where synchronization attains a maximum by fine-tuning the forcing frequency close to the relevant switching rate. In this work, we theoretically investigate the nonlinear single-vortex dynamics in a tilted cosine (multistable) washboard Pinning Potential at nonzero temperature in the presence of dc and ac currents of arbitrary amplitudes and frequency. The conditions for stochastic resonance to appear are derived on the basis of the exact solution of the corresponding Langevin equation for non-interacting vortices in terms of a matrix continued fraction. The nonlinear ac voltage response is analyzed as a function of temperature, dc bias, ac amplitude and frequency, with particular focus on the amplification of the external harmonic signal and its conversion to the third harmonics of the input frequency.
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vortex ratchet reversal in an asymmetric washboard Pinning Potential subject to combined dc and ac stimuli
arXiv: Superconductivity, 2013Co-Authors: Valerij A. Shklovskij, Oleksandr V. Dobrovolskiy, Vladimir V. SosedkinAbstract:The mixed-state resistive response of a superconductor thin film with an asymmetric washboard Pinning Potential subject to superimposed dc and ac currents of arbitrary amplitudes and frequency at finite temperature is theoretically investigated. The problem is considered in the single-vortex approximation, relying upon the exact solution of the Langevin equation in terms of a matrix continued fraction. The dc voltage response and the absorbed power in ac response are analyzed as functions of dc bias, ac current amplitude and frequency, in a wide range of corresponding dimensionless parameters. Predictions are made of (i) a reversal of the rectified voltage at small dc biases and strong ac drives and (ii) a non-monotonic enhancement of the absorbed power in the nonlinear ac response at far sub-dePinning frequencies. It is elucidated how and why both these effects appear due to the competition of the fixed internal and the tunable, dc bias-induced external asymmetry of the Potential as the only reason. This is distinct from other scenarios used for explaining the vortex ratchet reversal effect so far.
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determination of coordinate dependence of a Pinning Potential from a microwave experiment with vortices
Low Temperature Physics, 2013Co-Authors: Valerij A. Shklovskij, Oleksandr V. DobrovolskiyAbstract:The measurement of the complex impedance response accompanied by power absorption P(ω) in the radiofrequency and microwave ranges represents a most popular experimental method for the investigation of Pinning mechanisms and vortex dynamics in type-II superconductors. In the theory, the Pinning Potential (PP) well for a vortex must be a priori specified in order to subsequently analyze the measured data. We have theoretically solved the inverse problem at T = 0 K and exemplify how the coordinate dependence of a PP can be determined from a set of experimental curves P(ω|j0) measured at subcritical dc currents 0 < j0 < jc under a small microwave excitation j1 ≪ jc with frequency ω. We furthermore elucidate how and why the dePinning frequency ωp, which separates the non-dissipative (quasi-adiabatic) and the dissipative (high-frequency) regimes of small vortex oscillations in the PP, is reduced with increasing j0. The results can be directly applied to a wide range of conventional superconductors with a PP sub...
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Determination of coordinate dependence of a Pinning Potential from a microwave experiment with vortices
Low Temperature Physics, 2013Co-Authors: Valerij A. Shklovskij, Oleksandr V. DobrovolskiyAbstract:The measurement of the complex impedance response accompanied by power absorption P(ω) in the radiofrequency and microwave ranges represents a most popular experimental method for the investigation of Pinning mechanisms and vortex dynamics in type-II superconductors. In the theory, the Pinning Potential (PP) well for a vortex must be a priori specified in order to subsequently analyze the measured data. We have theoretically solved the inverse problem at T = 0 K and exemplify how the coordinate dependence of a PP can be determined from a set of experimental curves P(ω|j0) measured at subcritical dc currents 0
N. Zhu - One of the best experts on this subject based on the ideXlab platform.
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Flux creep and Pinning Potential distribution in zone‐melted YBa2Cu3Ox
Applied Physics Letters, 1991Co-Authors: Donglu Shi, K.c. Goretta, S. Salem-sugui, Paul J. Mcginn, W. H. Chen, N. ZhuAbstract:Magnetic relaxation data have been taken on zone‐melted and sintered YBa2Cu3Ox samples over wide temperature and magnetic field ranges. We have found that magnetic relaxation varies greatly in the samples with different microstructures and crystallographic orientations. Flux‐creep rates have been found to be reduced in the zone‐melted samples owing to large amounts of intragranular crystal defects such as edge dislocations and stacking faults. An important flux‐Pinning behavior related to the Pinning Potential distributions has been observed in the samples. The relationship between microstructural orientation and Pinning Potential distributions in YBa2Cu3Ox is discussed.
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flux creep and Pinning Potential distribution in zone melted yba2cu3ox
Applied Physics Letters, 1991Co-Authors: Donglu Shi, K.c. Goretta, Paul J. Mcginn, S Salemsugui, W Chen, N. ZhuAbstract:Magnetic relaxation data have been taken on zone‐melted and sintered YBa2Cu3Ox samples over wide temperature and magnetic field ranges. We have found that magnetic relaxation varies greatly in the samples with different microstructures and crystallographic orientations. Flux‐creep rates have been found to be reduced in the zone‐melted samples owing to large amounts of intragranular crystal defects such as edge dislocations and stacking faults. An important flux‐Pinning behavior related to the Pinning Potential distributions has been observed in the samples. The relationship between microstructural orientation and Pinning Potential distributions in YBa2Cu3Ox is discussed.
Donglu Shi - One of the best experts on this subject based on the ideXlab platform.
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Flux creep and Pinning Potential distribution in zone‐melted YBa2Cu3Ox
Applied Physics Letters, 1991Co-Authors: Donglu Shi, K.c. Goretta, S. Salem-sugui, Paul J. Mcginn, W. H. Chen, N. ZhuAbstract:Magnetic relaxation data have been taken on zone‐melted and sintered YBa2Cu3Ox samples over wide temperature and magnetic field ranges. We have found that magnetic relaxation varies greatly in the samples with different microstructures and crystallographic orientations. Flux‐creep rates have been found to be reduced in the zone‐melted samples owing to large amounts of intragranular crystal defects such as edge dislocations and stacking faults. An important flux‐Pinning behavior related to the Pinning Potential distributions has been observed in the samples. The relationship between microstructural orientation and Pinning Potential distributions in YBa2Cu3Ox is discussed.
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flux creep and Pinning Potential distribution in zone melted yba2cu3ox
Applied Physics Letters, 1991Co-Authors: Donglu Shi, K.c. Goretta, Paul J. Mcginn, S Salemsugui, W Chen, N. ZhuAbstract:Magnetic relaxation data have been taken on zone‐melted and sintered YBa2Cu3Ox samples over wide temperature and magnetic field ranges. We have found that magnetic relaxation varies greatly in the samples with different microstructures and crystallographic orientations. Flux‐creep rates have been found to be reduced in the zone‐melted samples owing to large amounts of intragranular crystal defects such as edge dislocations and stacking faults. An important flux‐Pinning behavior related to the Pinning Potential distributions has been observed in the samples. The relationship between microstructural orientation and Pinning Potential distributions in YBa2Cu3Ox is discussed.
Estefani Marchiori - One of the best experts on this subject based on the ideXlab platform.
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Reconfigurable superconducting vortex Pinning Potential for magnetic disks in hybrid structures
Scientific Reports, 2017Co-Authors: Estefani Marchiori, Peter J. Curran, Jangyong Kim, Nathan Satchell, Gavin Burnell, Simon J. BendingAbstract:High resolution scanning Hall probe microscopy has been used to directly visualise the superconducting vortex behavior in hybrid structures consisting of a square array of micrometer-sized Py ferromagnetic disks covered by a superconducting Nb thin film. At remanence the disks exist in almost fully flux-closed magnetic vortex states, but the observed cloverleaf-like stray fields indicate the presence of weak in-plane anisotropy. Micromagnetic simulations suggest that the most likely origin is an unintentional shape anisotropy. We have studied the Pinning of added free superconducting vortices as a function of the magnetisation state of the disks, and identified a range of different phenomena arising from competing energy contributions. We have also observed clear differences in the Pinning landscape when the superconductor and the ferromagnet are electron ically coupled or insulated by a thin dielectric layer, with an indication of non-trivial vortex-vortex interactions. We demonstrate a complete reconfiguration of the vortex Pinning Potential when the magnetisation of the disks evolves from the vortex-like state to an onion-like one under an in-plane magnetic field. Our results are in good qualitative agreement with theoretical predictions and could form the basis of novel superconducting devices based on reconfigurable vortex Pinning sites.
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Data for the publication: Reconfigurable superconducting vortex Pinning Potential for magnetic disks in hybrid structures
2017Co-Authors: Estefani MarchioriAbstract:This dataset contains raw data and images from Marchiori, E. et al. Reconfigurable superconducting vortex Pinning Potential for magnetic disks in hybrid structures. Sci. Rep. 7, 45182; doi: 10.1038/srep45182 (2017).