The Effect of Splayed Pins on Vortex Creep and Critical Currents

TL;DR

This study uses realistic simulations to analyze how splayed columnar pins influence vortex creep and critical currents, revealing complex effects on vortex dynamics and pinning efficiency.

Contribution

It provides new insights into how splayed pins affect vortex behavior, including suppression of creep and modulation of critical current enhancement.

Findings

Splaying pins suppresses vortex creep effectively.

Critical current enhancement is highly sensitive to splaying parameters.

Splaying influences vortex entanglement and kink nucleation.

Abstract

We study the effects of splayed columnar pins on the vortex motion using realistic London Langevin simulations. At low currents vortex creep is strongly suppressed, whereas the critical current j_c is enhanced only moderately. Splaying the pins generates an increasing energy barrier against vortex hopping, and leads to the forced entanglement of vortices, both of which suppress creep efficiently. On the other hand splaying enhances kink nucleation and introduces intersecting pins, which cut off the energy barriers. Thus the j_c enhancement is strongly parameter sensitive. We also characterize the angle dependence of j_c, and the effect of different splaying geometries.