Charge-orbital ordering and ferromagnetic chains in single-layered manganite crystals

Abstract

The temperature- and doping-induced variation of structural, magnetic, and transport properties has indicated unique switching of spin-charge-orbital states in the Mn-O sheets of single-layered manganite crystals, ${\mathrm{Nd}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{1+x}{\mathrm{MnO}}_{4}.$ In the composition range of $0.75<x<0.9,$ the magnetic ordering with alternate straight ferromagnetic chains occurs below ${T}_{N}\ensuremath{\approx}150\mathrm{K}$ in the orthorhombically distorted sheets which perhaps originate from the orbital ordering at 270 K. In the crystals with commensurate doping levels $(x=\frac{2}{3}$ and $\frac{3}{4}),$ additional superlattice spots are observed with the propagation vectors [\ensuremath{\delta}, \ensuremath{\delta}, 0] $[\ensuremath{\delta}\ensuremath{\approx}(1\ensuremath{-}x)/2],$ suggestive of the charge-orbital ordering with zig-zag ferromagnetic chains.