Evidence for largest room temperature magnetic signal from Co2+ in antiphase-free & fully inverted CoFe2O4 in multiferroic-ferrimagnetic BiFeO3-CoFe2O4 nanopillar thin films

•Antiphase-free and full inverted nanopillar thin films of cobalt ferrite inverse-spinel was obtained.•The largest x-ray magnetic circular dichroism signal of divalent cobalt at room temperature was observed.•X-ray absorption spectra and x-ray magnetic circular dichroism spectra were nicely reproduced by full atomic multiplet theory.•The enhanced performance of the cobalt ferrite inverse-spinel nanopillar thin film plausibly comes from its appropriate size.