Stripe order at low temperatures in La2−xSrxNiO4 with 0.289≲x≲0.5

Abstract

The stripe order in ${\mathrm{La}}_{2-x}{\mathrm{Sr}}_x{\mathrm{NiO}}_{4+\delta }$ with $0.289\lesssim x\lesssim 0.5$ was studied with neutron-scattering technique. At low temperatures, all samples exhibit hole stripe order. Incommensurability $\epsilon$ of the stripe order is approximately linear in the hole concentration $n_h=x+2\mathrm{}\delta$ up to $x=1/2,$ where $\delta$ denotes the off stoichiometry of oxygen atoms. The charge and spin ordering temperatures exhibit maxima at $n_h=\frac{1}{3},$ and both decrease beyond $n_h>\frac{1}{3}.$ For $\frac{1}{3}<~n_h\lesssim \frac{1}{2},$ the stripe ordering consists of the mixture of the $\epsilon =\frac{1}{3}$ stripe order and the $n_h=\frac{1}{2}$ charge/spin order.