Vortex dynamics in type II superconductors under strong pinning conditions

Abstract

We study effects of pinning on the dynamics of a vortex lattice in a type II superconductor in the strong-pinning situation and determine the force--velocity (or current--voltage) characteristic combining analytical and numerical methods. Our analysis deals with a small density $n_p$ of defects that act with a large force $f_p$ on the vortices, thereby inducing bistable configurations that are a characteristic feature of strong pinning theory. We determine the velocity-dependent average pinning-force density $⟨F_p(v)⟩$ and find that it changes on the velocity scale $v_p\sim f_p/\eta a_0^3$, where $\eta$ is the viscosity of vortex motion and $a_0$ the distance between vortices. In the small pin-density limit, this velocity is much larger than the typical flow velocity $v_c\sim F_c/\eta$ of the free vortex system at drives near the critical force-density $F_c=⟨F_p(v=0)⟩\propto n_p{f}_p$. As a result, we find a generic excess-force characteristic, a nearly linear force--velocity characteristic shifted by the critical force-density $F_c$; the linear flux-flow regime is approached only at large drives. Our analysis provides a derivation of Coulomb's law of dry friction for the case of strong vortex pinning.

24 pages, 12 figures

References in corpus (14)

• The Flux-Line Lattice in Superconductors
• Creep and depinning in disordered media
• Vortex-glass phases in type-II superconductors
• Weak- to strong pinning crossover
• Toward superconducting critical current by design
• Microscopic Derivation of Magnetic Flux Density Profiles, Magnetization Hysteresis Loops, and Critical Currents in Strongly Pinned Superconductors
• Theory and simulations on strong pinning of vortex lines by nanoparticles
• Edge and Bulk Transport in the Mixed State of a Type-II Superconductor
• Probing the pinning landscape in type-II superconductors via Campbell penetration depth
• Strong Pinning and Plastic Deformations of the Vortex Lattice
• Campbell response in type II superconductors under strong pinning conditions
• Campbell penetration in the critical state of type-II superconductors
• Pinning, Flux Diodes, and Ratchets for Vortices Interacting with Conformal Pinning Arrays
• Irreversible Dynamics of Abrikosov Vortices in Type-two Superconductors

Cited by in corpus (10)

• Perspective: Challenges and Transformative Opportunities in Superconductor Vortex Physics
• Peak effect due to competing vortex ground states in superconductors with large inclusions
• Strong pinning theory of thermal vortex creep in type II superconductors
• Thermal depinning and creep in strong pinning theory
• Experimental test of strong pinning and creep in current-voltage characteristics of type II superconductors
• Thermal hysteresis of the Campbell response as a probe for bulk pinscape spectroscopy
• The role of rare events in the pinning problem
• Dynamics of dissipative topological defects in coupled phase oscillators
• Depinning and flow of a vortex line in an uniaxial random medium
• Designing high-performance superconductors with nanoparticle inclusions: comparisons to strong pinning theory