Abstract
The magnetic ordering of perovskite has been studied by neutron powder diffraction and Mössbauer spectroscopy down to 2 K. From symmetry analysis, a chiral helical model and a collinear model are proposed to describe the magnetic structure. Both are commensurate, with propagation vector in space group. In the former model, the magnetic moments of Fe adopt the magnetic space group and have helical and antiferromagnetic ordering propagating along the axis. The model allows only a single Fe site, with a magnetic moment of 3.46(2) at 2 K. In the latter model, the magnetic moments of iron ions adopt the magnetic space group or and are aligned collinearly. The model allows the presence of two inequivalent Fe sites with magnetic moments of amplitude 3.26(3) and 3.67(2), respectively. The neutron-diffraction pattern is equally well fitted by either model. The Mössbauer spectroscopy study suggests a single charge state above the magnetic transition and a charge disproportionation into and below the magnetic transition. The compatibility of the magnetic structure models with the Mössbauer spectroscopy results is discussed.
- Received 23 February 2018
- Revised 30 April 2018
DOI:https://doi.org/10.1103/PhysRevB.97.174417
©2018 American Physical Society