Neutron diffraction on antiferromagnetic ordering in single-crystal BaFe2As2

TL;DR

This study uses neutron diffraction to investigate the antiferromagnetic order and structural phase transition in BaFe2As2 single crystals, revealing magnetic structure details and the influence of tin incorporation on transition temperatures.

Contribution

It provides detailed magnetic and structural characterization of BaFe2As2 single crystals, highlighting the effects of tin flux growth on transition temperatures and magnetic ordering.

Findings

Antiferromagnetic ordering occurs at ~90 K.

Magnetic moments align along the a axis.

Tin incorporation affects transition temperature.

Abstract

Neutron diffraction experiments have been carried out on a Sn-flux grown BaFe2As2 single crystal, the parent compound of the A-122 family of FeAs-based high-Tc superconductors. A tetragonal to orthorhombic structural phase transition and a three dimensional long-range antiferromagnetic ordering of the iron moment, with a unique magnetic propagation wavevector k = (1, 0, 1), have been found to take place at ~90 K. The magnetic moments of iron are aligned along the long a axis in the low temperature orthorhombic phase (Fmmm with b<a<c). Our results thus demonstrate that the magnetic structure of BaFe2As2 single crystal is the same as those in other A-122 iron pnictides compounds. We argue that the tin incorporation in the lattice is responsible for a smaller orthorhombic splitting and lower Neel temperature T_N observed in the experiment.