Absence of itinerant ferromagnetism in a cobalt-based oxypnictide

We report a layered transition-metal-ordered oxypnictide ${\mathrm{Sr}}_{2}{\mathrm{CrCoAsO}}_{3}$. The new material was synthesized by solid-state reactions under vacuum. It has an intergrowth structure with a perovskite-like ${\mathrm{Sr}}_{3}{\mathrm{Cr}}_{2}{\mathrm{O}}_{6}$ unit and ${\mathrm{ThCr}}_{2}{\mathrm{Si}}_{2}$-type ${\mathrm{SrCo}}_{2}{\mathrm{As}}_{2}$ block stacking coherently along the crystallographic $c$ axis. The measurements of electrical resistivity, magnetic susceptibility, and specific heat indicate metallic conductivity from the CoAs layers and short-range antiferromagnetic ordering in the ${\mathrm{CrO}}_{2}$ planes. No itinerant-electron ferromagnetism expected in CoAs layers is observed. This result, combined with the first-principles calculations and the previous reports of other CoAs-layer-based materials, suggests that the $\mathrm{Co}\ensuremath{-}\mathrm{Co}$ bond length plays a crucial role in the emergence of itinerant ferromagnetism.