Enhanced pinning in superconducting thin films with graded pinning landscapes

Motta, M.; Colauto, F.; Ortiz, W.A.; Fritzsche, Joachim; Cuppens, J.; Gillijns, Werner; Moshchalkov, Victor; Johansen, T. H.; Sanchez, Alvaro; Silhanek, Alejandro

doi:10.1063/1.4807848

Cited by 56 publications

(67 citation statements)

References 58 publications

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“…Experiments indicated that the triangular pinning arrays produced stronger pinning than the conformal arrays below the first matching field, while the conformal pinning array generated stronger pinning at higher fields [28]. Other experiments also found enhanced pinning by conformal arrays [29], and there have also been other studies of pinning arrays with spatial gradients [30,31]. In further simulations where a series of conformal arrays were placed back to back as illustrated in Fig.…”

Section: Introductionmentioning

confidence: 97%

Pinning, flux diodes and ratchets for vortices interacting with conformal pinning arrays

Wang

Xiao

Kwok

et al. 2017

Physica C: Superconductivity and its Applications

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A conformal pinning array can be created by conformally transforming a uniform triangular pinning lattice to produces a new structure in which the six-fold ordering of the original lattice is conserved but where there is a spatial gradient in the density of pinning sites. Here we examine several aspects of vortices interacting with conformal pinning arrays and how they can be used to create a flux flow diode effect for driving vortices in different directions across the arrays. Under the application of an ac drive, a pronounced vortex ratchet effect occurs where the vortices flow in the easy direction of the array asymmetry. When the ac drive is applied perpendicular to the asymmetry direction of the array, it is possible to realize a transverse vortex ratchet effect where there is a generation of a dc flow of vortices perpendicular to the ac drive due to the creation of a noise correlation ratchet by the plastic motion of the vortices. We also examine vortex transport simulations in experiments and compare the pinning effectiveness of conformal arrays to uniform triangular pinning arrays. We find that a triangular array generally pins the vortices more effectively at the first matching field and below, while the conformal array is more effective at higher fields where interstitial vortex flow occurs.

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Section: Introductionmentioning

confidence: 97%

Pinning, flux diodes and ratchets for vortices interacting with conformal pinning arrays

Wang

Xiao

Kwok

et al. 2017

Physica C: Superconductivity and its Applications

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show abstract

“…It was demonstrated that at low temperature and at magnetic fields higher than some critical value, H th , the magnetization curve becomes smooth and H th is sufficiently larger in the sample with an array of antidots [4]. The latter experiments were carried out with the field perpendicular to the film surface.…”

Section: A DC Magnetization Curvesmentioning

confidence: 99%

“…The Little-Parks effect and the quantization of trapped flux were intensively studied during the last fifty years [1][2][3]. Recent advances in nanotechnology have made it possible for studying experimentally superconducting properties of thin films with different arrays of antidots, see for example, [4] and references therein. In particular, for the observation of the aforementioned effects, cylinders or antidots of small diameter are required.…”

Section: Introductionmentioning

confidence: 99%

dc and ac magnetic properties of thin-walled Nb cylinders with and without a row of antidots

Tsindlekht¹,

Genkin²,

Felner³

et al. 2016

J. Phys.: Condens. Matter

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dc and ac magnetic properties of two thin-walled superconducting Nb cylinders with a rectangular cross-section are reported. Magnetization curves and the ac response were studied on as-prepared and patterned samples in magnetic fields parallel to the cylinder axis. A row of micron-sized antidots (holes) was made in the film along the cylinder axis. Avalanche-like jumps of the magnetization are observed for both samples at low temperatures for magnetic fields not only above Hc1, but in fields lower than Hc1 in the vortex-free region. The positions of the jumps are not reproducible and they change from one experiment to another, resembling vortex lattice instabilities usually observed for magnetic fields larger than Hc1. At temperatures above 0.66Tc and 0.78Tc the magnetization curves become smooth for the patterned and the as-prepared samples, respectively. The magnetization curve of a reference planar Nb film in the parallel field geometry does not exhibit jumps in the entire range of accessible temperatures. The ac response was measured in constant and swept dc magnetic field modes. Experiment shows that ac losses at low magnetic fields in a swept field mode are smaller for the patterned sample. For both samples the shapes of the field dependences of losses and the amplitude of the third harmonic are the same in constant and swept field near Hc3. This similarity does not exist at low fields in a swept mode.

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“…The appeal and advantage of superconducting systems is that the size and number of the particles can be tuned by changing the temperature and the magnetic field, respectively. In addition, the flexibility in the design and fabrication of artificial vortex traps in superconducting films has stimulated, during the past decade, an in-depth investigation of the interplay between pinning landscape and vortex pattern symmetry [16], influence of the pinning center's size and period [17][18][19][20], vortex rectification on a kagome-like array [21], competition between ordered and disordered defects [22][23][24], or pinning energy dispersion [25,26], to name a few.…”

Section: Introductionmentioning

confidence: 99%

Mapping degenerate vortex states in a kagome lattice of elongated antidots via scanning Hall probe microscopy

Xue

et al. 2017

Phys. Rev. B

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We investigate the degeneracy of the superconducting vortex matter ground state by directly visualizing the vortex configurations in a kagome lattice of elongated antidots via scanning Hall probe microscopy. The observed vortex patterns, at specific applied magnetic fields, are in good agreement with the configurations obtained using time-dependent Ginzburg-Landau simulations. Both results indicate that the long-range interaction in this nanostructured superconductor is unable to lift the degeneracy between different vortex states and the pattern formation is mainly ruled by the nearest-neighbor interaction. This simplification makes it possible to identify a set of simple rules characterizing the vortex configurations. We demonstrate that these rules can explain both the observed vortex distributions and the magnetic-field-dependent degree of degeneracy.

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Enhanced pinning in superconducting thin films with graded pinning landscapes

Cited by 56 publications

References 58 publications

Pinning, flux diodes and ratchets for vortices interacting with conformal pinning arrays

Pinning, flux diodes and ratchets for vortices interacting with conformal pinning arrays

dc and ac magnetic properties of thin-walled Nb cylinders with and without a row of antidots

Mapping degenerate vortex states in a kagome lattice of elongated antidots via scanning Hall probe microscopy

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