Spin and Lattice Structure of Single Crystal SrFe2As2

TL;DR

This study uses neutron scattering to analyze the spin and lattice structures of SrFe2As2, revealing a simultaneous structural phase transition and antiferromagnetic ordering, indicating these features are common in FeAs-based superconductor parents.

Contribution

It provides detailed neutron scattering data on SrFe2As2, demonstrating the concurrent structural and magnetic transitions and their similarity to other FeAs parent compounds.

Findings

Structural transition at 220K from tetragonal to orthorhombic

Development of collinear antiferromagnetic order at the transition

Static antiferromagnetic order is common in FeAs superconductor parents

Abstract

We use neutron scattering to study the spin and lattice structure on single crystals of SrFe2As2, the parent compound of the FeAs based superconductor (Sr,K)Fe2As2. We find that SrFe2As2 exhibits an abrupt structural phase transitions at 220K, where the structure changes from tetragonal with lattice parameters c > a = b to orthorhombic with c > a > b. At almost the same temperature, Fe spins in SrFe2As2 develop a collinear antiferromagnetic structure along the orthorhombic a-axis with spin direction parallel to this a-axis. These results are consistent with earlier work on the RFeAsO (R = rare earth elements) families of materials and on BaFe2As2, and therefore suggest that static antiferromagnetic order is ubiquitous for the parent compound of these FeAs-based high-transition temperature superconductors.