Revisiting the Magnetic Structure and Charge Ordering in La${}_{1/3}$Sr${}_{2/3}$FeO${}_3$ by Neutron Powder Diffraction and Mössbauer Spectroscopy

Abstract

The magnetic ordering of La${}_{1/3}$Sr${}_{2/3}$FeO${}_3$ perovskite has been studied by neutron powder diffraction and ${}^{57}$Fe 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 k = (0,0,1) in R-3c space group. In the former model, the magnetic moments of Fe adopt the magnetic space group P3${}_2$21 and have helical and antiferromagnetic ordering propagating along the c axis. The model allows only one Fe site, with a magnetic moment of 3.46(2) ${\mu }_{\mathrm{B}}$ at 2 K. In the latter model, the magnetic moments of iron ions adopt the magnetic space group C2/c or C2'/c' and are aligned collinearly. The model allows the presence of two inequivalent Fe sites with magnetic moments of amplitude 3.26(3) ${\mu }_{\mathrm{B}}$ and 3.67(2) ${\mu }_{\mathrm{B}}$, respectively. The neutron diffraction pattern is equally well fitted by either model. The Mössbauer spectroscopy study suggests a single charge state Fe${}^{3.66+}$ above the magnetic transition and a charge disproportionation into Fe${}^{(3.66-\zeta )+}$ and Fe${}^{(3.66+2\zeta )+}$ below the magnetic transition. The compatibility of the magnetic structure models with the Mössbauer spectroscopy results is discussed.

References in corpus (1)

• Destruction of Neel order and local spin spirals in insulating La_{2-x}Sr_xCuO_4

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• Room Temperature Dy Spin-Flop Switching in Strained DyFeO3 Thin Films
• First-principle Study of Multiple Metastable Charge Ordering States in La${}_{1/3}$Sr${}_{2/3}$FeO${}_3$