Universal magneto-orbital ordering in the divalent $A$-site quadruple perovskite manganites $A$Mn${}_7$O${}_{12}$ ($A$ = Ca, Sr, Cd, and Pb)

Abstract

Through analysis of variable temperature neutron powder diffraction data, we present solutions for the magnetic structures of SrMn${}_7$O${}_{12}$, CdMn${}_7$O${}_{12}$, and PbMn${}_7$O${}_{12}$ in all long-range ordered phases. The three compounds were found to have magnetic structures analogous to that reported for CaMn${}_7$O${}_{12}$. They all feature a higher temperature lock-in phase with \emph{commensurate} magneto-orbital coupling, and a delocked, multi-\textbf{k} magnetic ground state where \emph{incommensurate} magneto-orbital coupling gives rise to a constant-moment magnetic helix with modulated spin helicity. CdMn${}_7$O${}_{12}$ represents a special case in which the orbital modulation is commensurate with the crystal lattice and involves stacking of fully and partially polarized orbital states. Our results provide a robust confirmation of the phenomenological model for magneto-orbital coupling previously presented for CaMn${}_7$O${}_{12}$. Furthermore, we show that the model is universal to the $A^{2+}$ quadruple perovskite manganites synthesised to date, and that it is tunable by selection of the $A$-site ionic radius.

References in corpus (8)

• Giant improper ferroelectricity in the ferroaxial magnet CaMn7O12
• Multiferroic Properties of CaMn${}_7$O${}_{12}$
• Synthesis and characterization of multiferroic BiMn${}_7$O${}_{12}$
• Modulated spin helicity stabilized by incommensurate orbital density waves in a quadruple perovskite manganite
• Jahn-Teller distortions and charge, orbital and magnetic orders in NaMn7O12
• Orbital order in La0.5Sr1.5MnO4: beyond a common local Jahn-Teller picture
• Commensurate structural modulation in the charge- and orbitally-ordered phase of the quadruple perovskite (NaMn${}_3$)Mn${}_4$O${}_{12}$
• First-principles study of structurally modulated multiferroic CaMn${}_7$O${}_{12}$

Cited by in corpus (4)

• The magnetic structure and spin-flop transition in the A-site columnar-ordered quadruple perovskite $\mathrm{TmM}{\mathrm{n}}_3{\mathrm{O}}_6$
• Evolution of magneto-orbital order upon B-site electron doping in Na1-xCaxMn7O12 quadruple perovskite manganites
• Unusual effects of magnetic dilution in the ferrimagnetic columnar ordered $\mathrm{S}{\mathrm{m}}_2\mathrm{MnMnM}{\mathrm{n}}_{4-\mathrm{x}}\mathrm{T}{\mathrm{i}}_{\mathrm{x}}{\mathrm{O}}_{12}$ perovskites
• Competing electronic instabilities in the quadruple perovskite manganite PbMn${}_7$O${}_{12}$