Evidence for electromagnetic granularity in the polycrystalline iron-based superconductor LaO0.89F0.11FeAs

TL;DR

This study provides evidence that polycrystalline LaO0.89F0.11FeAs exhibits electromagnetic granularity at the grain scale, indicating weak intergrain coupling similar to high-Tc cuprates, with implications for understanding its superconducting properties.

Contribution

The paper demonstrates electromagnetic granularity in polycrystalline LaO0.89F0.11FeAs, highlighting weak coupling across grain boundaries, a novel insight into its superconducting behavior.

Findings

Bulk magnetization shows little hysteresis.

Remanent magnetization is size-independent.

Evidence of electromagnetic granularity at grain scale.

Abstract

The new rare-earth arsenate superconductors are layered, low carrier density compounds with many similarities to the high-Tc cuprates. An important question is whether they also exhibit weak-coupling across randomly oriented grain-boundaries. In this work we show considerable evidence for such weak-coupling by study of the dependence of magnetization in bulk and powdered samples. Bulk sample magnetization curves show very little hysteresis while remanent magnetization shows almost no sample size dependence, even after powdering. We conclude that these samples exhibit substantial electromagnetic granularity on a scale approximating the grain size, though we cannot yet determine whether this is intrinsic or extrinsic.