Huge magnetostriction in superconducting single-crystalline BaFe$_{1.908}$Ni$_{0.092}$As$_{2}$

TL;DR

This study reveals significant magnetostriction in BaFe$_{1.908}$Ni$_{0.092}$As$_{2}$ superconductors, linked to flux pinning, with implications for their high-field applications.

Contribution

It demonstrates that magnetostriction in this superconductor is primarily driven by flux pinning, supported by experimental data and modeling.

Findings

Huge longitudinal magnetostriction observed (~10^{-4})

High critical-current density due to strong bulk pinning

Magnetostriction explained by flux-pinning mechanism

Abstract

The performance of iron-based superconductors in high magnetic fields plays an important role for their practical application. In this work, we measured the magnetostriction and magnetization of BaFe$_{1.908}$Ni$_{0.092}$As$_{2}$ single crystals using pulsed magnetic fields up to 60 T and static magnetic fields up to 33 T, respectively. A huge longitudinal magnetostriction (of the order of 10$ ^{-4} $) was observed in the direction of the twin boundaries. The magnetization measurements evidence a high critical-current density due to strong bulk pinning. By using magnetization data with an exponential flux-pinning model, we can reproduce the magnetostriction curves qualitatively. This result shows that the magnetostriction of BaFe$_{1.908}$Ni$_{0.092}$As$_{2}$ can be well explained by a flux-pinning-induced mechanism.