Flux-pinning properties of superconducting films with arrays of blind holes

Raedts, Sophie; Silhanek, Alejandro; Bael, M. J. Van; Moshchalkov, Victor

doi:10.1103/physrevb.70.024509

Cited by 61 publications

(53 citation statements)

References 19 publications

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“…Further details about sample preparation can be found in Ref. 18. In all cases the magnetic field is applied perpendicularly to the plane of the film.…”

Section: Sample Detailsmentioning

confidence: 99%

First vortex entry into a perpendicularly magnetized superconducting thin film

et al. 2013

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In type-II superconductors, the flux-free state (Meissner state) may be invaded by vortices bearing quantized flux once H is above the lower critical field H c1 . However, the actual first flux penetration does not occur at H c1 due to the presence of a surface barrier and the fact that the Meissner state may also exist as a metastable state up to a larger (superheating) field. In this work we determine the field for the first vortex penetration in superconductors by directly imaging the first vortex threading a superconducting Pb film with antidots. We find that the first vortex penetration occurs when the surface superconducting currents reach the depairing current, locally breaking superconductivity and allowing a vortex to nucleate.

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“…Further details about sample preparation can be found in Ref. 18. In all cases the magnetic field is applied perpendicularly to the plane of the film.…”

Section: Sample Detailsmentioning

confidence: 99%

First vortex entry into a perpendicularly magnetized superconducting thin film

et al. 2013

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“…[10][11][12] This reflects in different (according to whether or not interstitial vortices are present) scenarios of the sample response to an excitation, as indeed observed in a great deal of macroscopic ac-susceptibility experiments. [13][14][15][16][17][18][19][20][21][22] The interpretation of the different dynamical regimes usually ig-nores the random pinning potential produced by sample inhomogeneities, considered negligible at the temperatures where the experiments are carried out. However, at least for experiments performed within the linear regime, where vortices are driven close to their equilibrium positions by very small driving forces, the weak material pinning might become important or even dominant.…”

Section: And References Therein)mentioning

confidence: 99%

Probing the low-frequency vortex dynamics in a nanostructured superconducting strip

et al. 2016

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We investigate by scanning susceptibility microscopy the response of a thin Pb strip, with a square array of submicron antidots, to a low-frequency ac magnetic field applied perpendicularly to the film plane. By mapping the local permeability of the sample within the field range where vortices trapped by the antidots and interstitial vortices coexist, we observed two distinct dynamical regimes occurring at different temperatures. At a temperature just below the superconducting transition, T /Tc = 0.96, the sample response is essentially dominated by the motion of highly mobile interstitial vortices. However, at a slightly lower temperature, T /Tc = 0.93, the interstitial vortices freeze up leading to a strong reduction of the ac screening length. We propose a simple model for the vortex response in this system which fits well to the experimental data. Our analysis suggests that the observed switching to the high mobility regime stems from a resonant effect, where the period of the ac excitation is just large enough to allow interstitial vortices to thermally hop through the weak pinning landscape produced by random material defects. This argument is further supported by the observation of a pronounced enhancement of the out-of-phase response at the crossover between both dynamical regimes.

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“…It is now well established that these artificial pinning centers (i) hold great potential for enhancing the critical parameters of the sample and (ii) give rise to different kinds of vortex behavior that is not observed in the presence of random pinning. In this respect, arrays of microholes (antidots) 1,2,3,4,5,6,7,8,9,10,11,12 and submicron magnetic dots, 13,14,15 have been studied, as their presence in the SC film strongly modifies the vortex structure compared to the one in non-patterned films. 16,17 Direct imaging experiments, 1 magnetization and transport measurements, 2,3,4,5 and theoretical simulations 18,19,20,21,22 of vortex structures in samples with periodic pinning centers have shown that the vortices form highly ordered configurations at integer H n = nΦ 0 /S and at some fractional H p/q = p q Φ 0 /S (n,p,q being integers) matching fields, where Φ 0 = hc/2e = 2.07 · 10 −7 Gcm 2 is the flux quantum, and S is the area of the primitive cell of the artificial lattice.…”

Section: Introductionmentioning

confidence: 99%

“…blind holes). 10 Most of the experiments on perforated superconducting films are carried out in the effective type-II limit (κ * = λ 2 /dξ ≫ 1/ √ 2, d being the thickness of the superconducting film and λ the magnetic penetration depth). In this regime, the vortices act like charged point particles and their interaction with periodic pinning potential can be described using molecular dynamic simulations.…”

Section: Introductionmentioning

confidence: 99%

Vortex configurations and critical parameters in superconducting thin films containing antidot arrays: Nonlinear Ginzburg-Landau theory

Berdiyorov

Miloševıć²,

Peeters³

2006

Phys. Rev. B

110

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Using the non-linear Ginzburg-Landau (GL) theory, we obtain the possible vortex configurations in superconducting thin films containing a square lattice of antidots. The equilibrium structural phase diagram is constructed which gives the different ground-state vortex configurations as function of the size and periodicity of the antidots for a given effective GL parameter κ * . Giant-vortex states, combination of giant-and multi-vortex states, as well as symmetry imposed vortex-antivortex states are found to be the ground state for particular geometrical parameters of the sample. The antidot occupation number no is calculated as a function of related parameters and comparison with existing expressions for the saturation number ns and with experimental results is given. For a small radius of antidots a triangular vortex lattice is obtained, where some of the vortices are pinned by the antidots and some of them are located between them. Transition between the square pinned and triangular vortex lattices is given for different values of the applied field. The enhanced critical current at integer and rational matching fields is found, where the level of enhancement at given magnetic field directly depends on the vortex-occupation number of the antidots. For certain parameters of the antidot lattice and/or temperature the critical current is found to be larger for higher magnetic fields. Superconducting/normal H − T phase boundary exhibits different regimes as antidots are made larger, and we transit from a plain superconducting film to a thin-wire superconducting network. Presented results are in good agreement with available experiments and suggest possible new experiments.

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Flux-pinning properties of superconducting films with arrays of blind holes

Cited by 61 publications

References 19 publications

First vortex entry into a perpendicularly magnetized superconducting thin film

First vortex entry into a perpendicularly magnetized superconducting thin film

Probing the low-frequency vortex dynamics in a nanostructured superconducting strip

Vortex configurations and critical parameters in superconducting thin films containing antidot arrays: Nonlinear Ginzburg-Landau theory

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