Study on magnetism and electronic structure of new layered compound Sr₃Sc₂O₅Co₂As₂ with body-centered crystal structure

We synthesized a polycrystalline sample of a new compound, Sr₃Sc₂O₅Co₂As₂, and measured its magnetization and electric resistivity. The measurement results showed that Sr₃Sc₂O₅Co₂As₂ is the first example of a weak itinerant electronic ferromagnet among the compounds with CoAs layers, whose crystal structure belongs to the space group I4/mmm and which have divalent Co ions. By performing electronic structure calculations, we demonstrated the realization of the ferromagnetic ground state in Sr₃Sc₂O₅Co₂As₂ and also showed the similarity of its electronic structure to those of ferromagnets with CoAs layers. Our results clarified that compounds with CoAs layers can be universally understood in terms of itinerant ferromagnetism. Our findings will also shed light on the mystery of why AeCo₂Pn₂ (Ae = Sr, Ba, Pn = P, As) and Sr₂CrO₂Co₂As₂ do not exhibit ferromagnetism even though they seem to have the potential to do so. (author)