Vortex pinning : a probe for nanoscale disorder in iron-based superconductors

TL;DR

This paper investigates how vortex pinning in iron-based superconductors reveals details about nanoscale and atomic-scale disorder, providing insights into impurity effects and quasiparticle scattering.

Contribution

It introduces a method to probe nanoscale disorder in IBS through vortex pinning analysis, linking flux pinning behavior to impurity-induced heterogeneity.

Findings

Strong flux pinning from nm-scale heterogeneity causes disordered vortex ensembles.

Atomic-scale disorder from dopants results in weak collective pinning and a field-independent jcoll.

Vortex pinning analysis estimates quasiparticle scattering rates.

Abstract

The pinning of quantized flux lines, or vortices, in the mixed state is used to quantify the effect of impurities in iron-based superconductors (IBS). Disorder at two length scales is relevant in these materials. Strong flux pinning resulting from nm-scale heterogeneity of the superconducting properties leads to the very disordered vortex ensembles observed in the IBS, and to the pronounced maximum in the critical current density jc at low magnetic fields. Disorder at the atomic scale, most likely induced by the dopant atoms, leads to "weak collective pinning" and a magnetic field-independent contribution jcoll. The latter allows one to estimate quasi-particle scattering rates.