Susceptibility anisotropy in an iron arsenide superconductor revealed by x-ray diffraction in pulsed magnetic fields

TL;DR

This study uses x-ray diffraction in pulsed magnetic fields to reveal anisotropic susceptibility in an iron arsenide superconductor, highlighting magnetoelastic coupling and electronic anisotropy related to structural transitions.

Contribution

It demonstrates magnetic detwinning effects and susceptibility anisotropy in Ba(Fe{1-x}Co{x})2As2, showing how these properties evolve with temperature and magnetic field, especially across the structural transition.

Findings

Anisotropy in in-plane susceptibility develops at the structural phase transition.

Detwinning increases smoothly with decreasing temperature, achieving single-domain states.

No detwinning observed within the superconducting phase at accessible fields.

Abstract

In addition to unconventional high-Tc superconductivity, the iron arsenides exhibit strong magnetoelastic coupling and a notable electronic anisotropy within the a-b plane. We relate these properties by studying underdoped Ba(Fe{1-x}Co{x})2As2 by x-ray diffraction in pulsed magnetic fields up to 27.5 Tesla. We exploit magnetic detwinning effects to demonstrate anisotropy in the in-plane susceptibility, which develops at the structural phase transition despite the absence of magnetic order. The degree of detwinning increases smoothly with decreasing temperature, and a single- domain condition is realized over a range of field and temperature. At low temperatures we observe an activated behavior, with a large hysteretic remnant effect. Detwinning was not observed within the superconducting phase for accessible magnetic fields.