Surface effects on moving vortices in superconducting stripes

Using molecular dynamics techniques, we simulate the vortex behavior in a type II superconducting strip in the presence of triangular and two types of conformal pinning arrays, one with a pinning gradient perpendicular to the driving force (C1) and the other parallel (C2), at zero temperature. A transport force is applied in the infinite direction of the strip, and the magnetic field is increased until the rate between the density of vortices (n v ) and pinning (n p ) reaches n v /n p = 1.5. Our results show a monotonic increase, by steps, of the vortex density with the applied magnetic field. Besides, each pinning lattice presents a different vortex penetration delay. For the triangular pinning array, different than the case of infinite films, here the system exhibits only one pronounced depinning force peak at n v /n p = 1. However, the depinning force peak is present for only one value of field, in the range of fields where n v /n p = 1 is stable. For the case of conformal pinning arrays, in analogy to what is observed in infinite films, no commensurability depinning force peaks were found. In the present case, the C1 array is more efficient at low fields, all arrays are equivalent in the intermediate fields, and the C2 array is more efficient for high fields. We also show that for the C1 array at high fields, vortices depin following the conformal arches, from the edge to the center. For the C2 array, the depinning force is higher when compared to that of C1, because this particular conformal structure prevents the formation of easy vortex flow channels.

“…The second term on the right is the vortex-pinning interaction, which is described as a Gaussian function [32,33,37,54,77]:…”

Section: Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Surface Effects on the Dynamic Behavior of Vortices in Type II Superconducting Strips with Periodic and Conformal Pinning Arrays

Vizarim

Carlone

Verga

et al. 2017

“…Theoretical studies demonstrated that the size effects influence properties like magnetization, vortex lattice geometry, critical currents, and dynamical phases for superconducting strips [45][46][47][48][49][50][51][52][53]. As an example, Carneiro [45] analyzed the minimum energy configuration for several vortex lattices in superconducting thin strips, observing changes in the vortex configuration with the increase of the applied magnetic field.…”

mentioning

confidence: 99%

Vortex Dynamic Phases in Type II Superconducting Strips with Regular and Flattened Triangular Pinning Arrays

Verga

Vizarim

Carlone

et al. 2018

The dynamic behavior of vortices in type II superconducting infinite strips is simulated with two types of triangular pinning lattices: the regular one and a flattened triangular array that mimics the vortex lattice in a superconducting strip in the absence of a pinning array. The calculations were made at zero temperature and perpendicular magnetic field. The size effects are investigated for several strip widths maintaining the density and size of pinning centers unchanged. A driving force is applied in the infinite direction to analyze the depinning process and the different dynamic regimes. For the regular triangular pinning lattice, we found that there is a great richness of vortex dynamical phases because depending on strip width, part of the vortices may stabilize in different interstitial positions and the depinning process depends on the commensurability of each vortex chain. For the flattened triangular lattice, the system exhibits one ordered moving phase for narrower strips and two moving phases for the larger strip. As the transport force increases, vortices in the larger strip go from a disordered to an ordered phase. Moreover, the flattened lattice shows a much higher critical depinning force than the regular one due to commensurability effects.

Role of Interstitial Pinning in the Dynamical Phases of Vortices in Superconducting Films

Simões

Venegas

Mello

2012

We analyze the vortex dynamics in superconducting thin films with a periodic array of pinning centers. In particular, we study the effect of anisotropy for a Kagomé pinning network when longitudinal and transverse transport currents are applied. By solving the equations of motion for the vortex array numerically at zero temperature we find different phases for the vortex dynamics depending on the pinning and driving force. An unusual sequence of peaks along and perpendicular to the main hexagonal lattice axes is observed for the differential resistance reflecting the anisotropy of the transport properties and the complex behavior of the vortex system. This behavior may be understood in terms of interstitial pinning vacancies, which create channels of vortices with different pinning strength.