Numerical investigation of critical states in superposed superconducting films

Burger, Loïc; Veshchunov, Ivan S.; Tamegai, T.; Silhanek, Alejandro; Nagasawa, Shuichi; Hidaka, Mutsuo; Vanderheyden, Benoît

doi:10.1088/1361-6668/ab4b18

Cited by 4 publications

(2 citation statements)

References 27 publications

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“…They state that current flows in the superconductor at its critical value wherever there are vortices penetrated. For the simpler Bean model [33], J c is independent of the local flux density, B z , however, a flux-dependent J c (B z ) may be essential to describe some subtle features [36][37][38][39]. In general, knowledge of the flux distribution provides information about the current distribution throughout the specimen [40][41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

Magnetic flux penetration in nanoscale wedge-shaped superconducting thin films

et al. 2022

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Thickness uniformity is regarded as an important parameter in designing thin film devices. However, some applications based on films with nonuniform thickness have recently emerged, such as gas sensors and optimized materials based on the gradual change of film composition. This work deals with superconducting Pb thin films with a thickness gradient prepared with the aid of a diffuse stencil mask. Atomic force microscopy and energydispersive x-ray spectroscopy show variations in the range 90 nm-154 nm. Quantitative magneto-optical images reveal interesting features during both the abrupt and the smooth penetration regimes of magnetic flux, as well as the thickness-dependent critical current density (J c ). In addition, we observe a gradual superconducting transition as the upper critical field is progressively reached for certain thicknesses. Furthermore, the hysteresis observed for triggering flux avalanches when increasing and decreasing magnetic fields is also accounted for by the J c profile evolution along the thickness gradient. Numerical simulations based on the thermomagnetic model are in fair agreement with the experimental data. These findings demonstrate that wedge-shaped films are a viable approach to investigate, in a continuous fashion, thickness-dependent properties of superconducting materials.

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Section: Introductionmentioning

confidence: 99%

Magnetic flux penetration in nanoscale wedge-shaped superconducting thin films

et al. 2022

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“…However, many of these software have their own shortcomings when applied to superconductivity: the non-linear resistivity cannot always be implemented depending on the software used and when it is possible, the conver-gence of the solution is not always favorable. Several researches have used the H-φ formulation to simulate superconductors in open-source software such as GetDP [33][34][35], which provides greater customizability than COMSOL, but with a steeper learning curve and less support than commercial software.…”

Section: Introductionmentioning

confidence: 99%

Implementation of the H-$ϕ$ formulation in COMSOL Multiphysics for simulating the magnetization of bulk superconductors and comparison with the H-formulation

Arsenault,

Sirois,

Grilli

2020

Preprint

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The H-formulation, used abundantly for the simulation of high temperature superconductors, has shown to be a very versatile and easily implementable way of modeling electromagnetic phenomena involving superconducting materials. However, the simulation of a full vector field in current-free domains unnecessarily adds degrees of freedom to the model, thereby increasing computation times. In this contribution, we implement the well known H-φ formulation in COMSOL Multiphysics in order to compare the numerical performance of the H and H-φ formulations in the context of computing the magnetization of bulk superconductors. We show that the H-φ formulation can reduce the number of degrees of freedom and computation times by nearly a factor of two for a given relative error. The accuracy of the magnetic fields obtained with both formulations are demonstrated to be similar. The computational benefits of the H-φ formulation are shown to far outweigh the added complexity of its implementation, especially in 3-D. Finally, we identify the ideal element orders for both H and H-φ formulations to be quartic in 2-D and cubic in 3-D, corresponding to the highest element orders implementable in COMSOL.

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Enhancing the effective critical current density in a Nb superconducting thin film by cooling in an inhomogeneous magnetic field

Chaves

Araújo

Carmo

et al. 2021

Applied Physics Letters

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Quantitative magneto-optical imaging of a type-II superconductor thin film cooled under zero, homogeneous, and inhomogeneous applied magnetic fields indicates that the latter procedure leads to an enhancement of the screening capacity. Such an observation is corroborated by both B-independent and B-dependent critical state model analyses. Furthermore, repulsive (attractive) vortex-(anti)vortex interactions were found to have a decisive role in the shielding ability, with initial states prepared with vortices resulting in a shorter magnetic flux front penetration depth than those prepared with antivortices. The proposed strategy could be implemented to boost the performance of thin superconducting devices.

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Numerical investigation of critical states in superposed superconducting films

Cited by 4 publications

References 27 publications

Magnetic flux penetration in nanoscale wedge-shaped superconducting thin films

Magnetic flux penetration in nanoscale wedge-shaped superconducting thin films

Implementation of the H-$ϕ$ formulation in COMSOL Multiphysics for simulating the magnetization of bulk superconductors and comparison with the H-formulation

Enhancing the effective critical current density in a Nb superconducting thin film by cooling in an inhomogeneous magnetic field

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