Direct imaging of commensurate vortex structures in ordered antidot arrays

Григоренко, А. Н.; Howells, G. D.; Bending, S. J.; Bekaert, Joost; Bael, M. J. Van; Look, Lieve Van; Moshchalkov, Victor; Bruynseraede, Y.; Borghs, Gustaaf; Kaya, İsmet I.; Stradling, R. A.

doi:10.1103/physrevb.63.052504

Cited by 65 publications

(42 citation statements)

References 15 publications

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“…1h). This is similar to a superconductor with antidots as pinning centres, where multiquanta vortices are formed and the interaction between pinning centre and vortices becomes purely repulsive only when a saturation number n s is reached [31][32][33][34] .…”

Section: Resultsmentioning

confidence: 99%

Bound vortex dipoles generated at pinning centres by Meissner current

Ge¹,

Gutiérrez²,

Gladilin

et al. 2015

Nat Commun

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One of the phenomena that make superconductors unique materials is the MeissnerOchsenfeld effect. This effect results in a state in which an applied magnetic field is expelled from the bulk of the material because of the circulation near its surface of resistance-free currents, also known as Meissner currents. Notwithstanding the intense research on the Meissner state, local fields due to the interaction of Meissner currents with pinning centres have not received much attention. Here we report that the Meissner currents, when flowing through an area containing a pinning centre, generate in its vicinity two opposite sense current half-loops producing a bound vortex-antivortex pair, which eventually may transform into a fully developed vortex-antivortex pair ultimately separated in space. The generation of such vortex dipoles by Meissner currents is not restricted to superconductors; similar topological excitations may be present in other systems with Meissner-like phases.

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Section: Resultsmentioning

confidence: 99%

Bound vortex dipoles generated at pinning centres by Meissner current

Ge¹,

Gutiérrez²,

Gladilin

et al. 2015

Nat Commun

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“…It is important to emphasize that the mere existence of regular patterns in the above field-cooling (FC) experiments is indicative of a low dispersion in pinning energy among different antidots and the fingerprint of a highly homogeneous sample. [22][23][24] …”

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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“…The antidots had circular (square) shape with radius R = 330nm (size a = 0.8µm), the film thickness was d = 80nm (d = 100nm) and the coherence length at zero temperature was estimated ξ(0) = 30nm (ξ(0) = 33nm) in Ref. 11 (Ref. 8 ).…”

Section: Vortex Lattices -Influence Of Geometrical Parametersmentioning

confidence: 99%

“…Let us first discuss the results for the sample of Ref. 11 , where the experimentally obtained saturation number was n s =2 at T /T c0 = 0.77. Fig.…”

Section: Vortex Lattices -Influence Of Geometrical Parametersmentioning

confidence: 99%

“…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%

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

Berdiyorov

Miloševıć²,

Peeters³

2006

Phys. Rev. B

109

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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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Direct imaging of commensurate vortex structures in ordered antidot arrays

Cited by 65 publications

References 15 publications

Bound vortex dipoles generated at pinning centres by Meissner current

Bound vortex dipoles generated at pinning centres by Meissner current

First vortex entry into a perpendicularly magnetized superconducting thin film

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

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