Synthesis, structures, and magnetic properties of novel Roddlesden–Popper homologous series Srn+1ConO3n+1 (n=1,2,3,4, and [infinity])

Roddlesden–Popper homologous series Srn+1ConO3n+1 (n=1,2,3,4, and [infinity]) compounds were successfully synthesized by a high pressure and high temperature technique. Structure refinement revealed that these compounds crystallize in tetragonal structures, while the compound n=[infinity] is cubic. These compounds are ferromagnetic with the Curie temperature decreasing from 255 K for n=1 to about 200 K for n=2–4 and down to 175 K for SrCoO3. Co4+ ions present as intermediate spin states for n=1–4, but in the low spin state in SrCoO3. Negative magnetoresistance was observed for Sr2CoO4 and found to be larger than that for SrCoO3.