Tearing transition and plastic flow in superconducting thin films

Abstract

A new class of artificial atoms, such as synthetic nanocrystals or vortices in superconductors, naturally self-assemble into ordered arrays. This property makes them applicable to the design of novel solids, and devices whose properties often depend on the response of such assemblies to the action of external forces. Here we study the transport properties of a vortex array in the Corbino disk geometry by numerical simulations. In response to an injected current in the superconductor, the global resistance associated to vortex motion exhibits sharp jumps at two threshold current values. The first corresponds to a tearing transition from rigid rotation to plastic flow, due to the reiterative nucleation around the disk center of neutral dislocation pairs that unbind and glide across the entire disk. After the second jump, we observe a smoother plastic phase proceeding from the coherent glide of a larger number of dislocations arranged into radial grain boundaries.The production of ordered self-assembled structures of various materials as diverse as synthetic nanocrystals, magnetic colloids, charged particles in Coulomb crystals, proteins and surfactants, or vortices in type II superconductors and in Bose-Einstein condensates, has attracted much interest for various fundamental and practical reasons which are ultimately concerned with their collective properties (optical, magnetic, mechanical, or transport 1

Grain boundaries in vortex matter

“…[35][36][37] For instance, the vortex plastic flow in the Corbino disk geometry is characterized by radial grain boundaries sliding in the tangential direction. 35 In addition, recent numerical simulations indicate the presence of an intermediate polycrystalline phase before the melting transition. 36,37 This behavior was observed using different numerical methods in two dimensions 36 and in presence of columnar disorder.…”

Laminar Flow of a Sheared Vortex Crystal: Scars in Flat Geometry

“…Finally, at higher currents the flow is laminar. Theoretical [6,7] and numerical [8] studies have clarified the role played by topological defects in these transitions, revealing that when the flow is laminar dislocations are arranged into long radial grain boundary (GB) scars [8]. Similar dislocation scars have received much attention in recent years in the study of crystalline materials on curved manifolds.…”

“…[8], the vortex lattice rotates rigidly below a critical current I 0 after which it deforms plastically. Here, we focus on the behavior of a second threshold current I 1 , above which vortex flow becomes laminar; i.e., the velocity profiles vðrÞ follow the driving force profile decaying as 1=r.…”

The position-dependent vortex dynamics in the asymmetric superconducting ring

“…31 Very recently, we investigated the vortex dynamics in a square superconducting ring. 32 The vortices can move without crossing the sample boundaries at a fixed applied field, which is analogous to the Corbino disk, [33][34][35][36][37][38][39][40] However, when the inner hole deviated from the center, there will exhibited significantly difference vortex dynamical phenomenon. For asymmetric superconducting ring with an off-center hole, the vortex creation/disappearance point will shift away from the middle point of the edges as in the symmetric ring.…”