Anisotropic pinning enhancement in Nb films with arrays of submicrometric Ni lines

Jaque, D.; González, E. M.; Martín, José Ignacio; Anguita, José V.; Vicent, J. L.

doi:10.1063/1.1512947

Cited by 31 publications

(37 citation statements)

References 20 publications

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“…Furthermore, it is possible to see well defined anisotropic behavior in the critical forces, mainly for the peaks at B/B ϕ =1/3, 1/2, and 2/3. Anisotropic behavior was previously observed in experimental and theoretical for infinite films, but for higher magnetic fields and different system parameters [13][14][15][16]19,21 . Our simulations also show that, in general, F c y > F c x for fractional matching fields, with the exception of B/B ϕ =1/3.…”

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confidence: 86%

Critical Forces at Fractional Matching Fields in Superconducting Thin Films with Triangular Pinning Lattice

et al. 2017

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We numerically study the commensurability effects in the critical forces in a type II superconducting thin film with vortices under the influence of a triangular pinning lattice at sub matching fields and zero temperature. The analysis is made applying a transport force in two mutually perpendicular directions and magnetic field perpendicular to the film surface. The results show critical force peaks at fractional matching fields, as a direct consequence of the commensurability effects. For the first time, we simulate the sequence of force peaks detected in recent experiments. Anisotropic effects in the critical forces are also reported, in analogy with that found at higher fields.

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confidence: 86%

Critical Forces at Fractional Matching Fields in Superconducting Thin Films with Triangular Pinning Lattice

et al. 2017

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“…Some experiments examining vortices in q1D periodic pinning structures show that peaks in the critical current occur at certain fillings 53,[55][56][57] in regimes where the pinning is weak, whereas other experiments performed in the strong pinning limit reveal more step-like features in the critical current. This suggests that the experiments in the strong pinning limit are producing buckling transitions 58 .…”

Section: Pinned Phasesmentioning

confidence: 99%

“…In general, the colloidal studies focused on the case where the particle lattice constant a is larger than the substrate lattice constant w. Martinoli et al investigated vortex pinning in samples with a 1D periodic thickness modulation [53][54][55] and observed broad commensuration peaks in the depinning threshold that were argued to be correlated with the formation of ordered vortex arrangements that could align with the substrate periodicity. Other vortex studies in similar samples also revealed peaks in the critical depinning force associated with commensuration effects 56,57 , while studies of vortices interacting with 1D magnetic strips showed that commensurate conditions were marked by depinning steps rather than peaks 58 . Under an applied dc drive, depinning transitions occur into a sliding state, and when an additional ac drive is added to the dc drive, a series of Shapiro steps in the voltage-current curves appears when the frequency of the oscillatory motion of the vortex lattice moving over the periodic substrate locks with the ac driving frequency 54 .…”

Section: Introductionmentioning

confidence: 99%

Orientational ordering, buckling, and dynamic transitions for vortices interacting with a periodic quasi-one-dimensional substrate

2016

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We examine the statics and dynamics of vortices in the presence of a periodic quasi-one dimensional substrate, focusing on the limit where the vortex lattice constant is smaller than the substrate lattice period. As a function of the substrate strength and filling factor, within the pinned state we observe a series of order-disorder transitions associated with buckling phenomena in which the number of vortex rows that fit between neighboring substrate maxima increases. These transitions coincide with steps in the depinning threshold, jumps in the density of topological defects, and changes in the structure factor. At the buckling transition the vortices are disordered, while between the buckling transitions the vortices form a variety of crystalline and partially ordered states. In the weak substrate limit, the buckling transitions are absent and the vortices form an ordered hexagonal lattice that undergoes changes in its orientation with respect to the substrate as a function of vortex density. At intermediate substrate strength, certain ordered states appear that are correlated with peaks in the depinning force. Under an applied drive the system exhibits a rich variety of distinct dynamical phases, including plastic flow, a density-modulated moving crystal, and moving floating solid phases. We also find a dynamic smectic-to-smectic transition in which the smectic ordering changes from being aligned with the substrate to being aligned with the external drive. The different dynamical phases can be characterized using velocity histograms and the structure factor. We discuss how these results are related to recent experiments on vortex ordering in thin films with periodic thickness modulations. Our results should also be relevant for other types of systems such as ions, colloids, or Wigner crystals interacting with periodic quasi-one-dimensional substrates.

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“…The pinning force thus induced was minimal for flux flow parallel to the grooves and maximal for perpendicular flux flow. Jacue et al [54] fabricated submicron Ni stripes by electron beam lithography underneath superconducting Nb films and showed that the stripes induce a strong anisotropy in the dissipative behavior. When the vortices moved perpendicular to the Ni stripes the resistance dropped by several orders of magnitude in comparison with the dissipation of vortices moving parallel to them.…”

Section: Systems With Washboard Pinning Nanolandscapesmentioning

confidence: 99%

Abrikosov fluxonics in washboard nanolandscapes

Dobrovolskiy

2017

Physica C: Superconductivity and its Applications

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Abrikosov fluxonics, a domain of science and engineering at the interface of superconductivity research and nanotechnology, is concerned with the study of properties and dynamics of Abrikosov vortices in nanopatterned superconductors, with particular focus on their confinement, manipulation, and exploitation for emerging functionalities. Vortex pinning, guided vortex motion, and the ratchet effect are three main fluxonic "tools" which allow for the dynamical (pinned or moving), the directional (angle-dependent), and the orientational (current polaritysensitive) control over the fluxons, respectively. Thanks to the periodicity of the vortex lattice, several groups of effects emerge when the vortices move in a periodic pinning landscape: Spatial commensurability of the location of vortices with the underlying pinning nanolandscape leads to a reduction of the dc resistance and the microwave loss at the so-called matching fields. Temporal synchronization of the displacement of vortices with the number of pinning sites visited during one half ac cycle manifests itself as Shapiro steps in the current-voltage curves. Delocalization of vortices oscillating under the action of a high-frequency ac drive can be tuned by a superimposed dc bias. In this short review a choice of experimental results on the vortex dynamics in the presence of periodic pinning in Nb thin films is presented. The consideration is limited to one particular type of artificial pinning structures -directly written nanolandscapes of the washboard type, which are fabricated by focused ion beam milling and focused electron beam induced deposition. The reported results are relevant for the development of fluxonic devices and the reduction of microwave losses in superconducting planar transmission lines.

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Anisotropic pinning enhancement in Nb films with arrays of submicrometric Ni lines

Cited by 31 publications

References 20 publications

Critical Forces at Fractional Matching Fields in Superconducting Thin Films with Triangular Pinning Lattice

Critical Forces at Fractional Matching Fields in Superconducting Thin Films with Triangular Pinning Lattice

Orientational ordering, buckling, and dynamic transitions for vortices interacting with a periodic quasi-one-dimensional substrate

Abrikosov fluxonics in washboard nanolandscapes

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