Year: 2016
Type: article
Abstract: Crystal and magnetic structures of the high-pressure stabilized perovskite phase of ${\mathrm{TlMnO}}_{3}$ have been studied by neutron powder diffraction. The crystal structure involves two types of primary structural distortions: ${a}^{+}{b}^{\ensuremath{-}}{b}^{\ensuremath{-}}$ octahedral tilting and antiferrodistortive type of orbital ordering, whose common action reduces the symmetry down to triclinic $P\overline{1}$. The orbital pattern and the way it is combined with the octahedral tilting are different from the family of ${\mathrm{LnMnO}}_{3}$ (Ln = lanthanide or Y) manganites who share with ${\mathrm{TlMnO}}_{3}$ the same tilting scheme. The experimentally determined magnetic structure with the $\mathbit{k}=(1/2,0,1/2)$ propagation vector and ${P}_{S}\overline{1}$ symmetry implies anisotropic exchange interactions with a ferromagnetic coupling within the $(1,0,\overline{1})$ planes and an antiferromagnetic one between them (A type). The spins in the primary magnetic mode were found to be confined close to the $(1,0,\overline{1})$ plane, which underlines the predominant role of the single ion anisotropy with the local easy axes of ${\mathrm{Mn}}^{3+}$ following the Jahn-Teller distortions of the octahedra. In spite of the same octahedral tilting scheme in the perovskite structures of both ${\mathrm{LnMnO}}_{3}$ and ${\mathrm{TlMnO}}_{3}$ manganites, a coupling of the secondary ferromagnetic component to the primary A-type spin configuration through antisymmetric exchange interaction is allowed in the former and forbidden in the latter cases.
Language: Latvian
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2531182258