Superconductivity in LiFeO2Fe2Se2 with anti-PbO-type spacer layers

We report on a superconductor LiFeO${}_{2}$Fe${}_{2}$Se${}_{2}$ with ${T}_{\mathrm{c}}\ensuremath{\sim}43$ K, synthesized via the hydrothermal method. The anti-PbO-type spacer layer of LiFeO${}_{2}$ has been successfully intercalated between the anti-PbO-type FeSe layer, which results in a high-${T}_{\mathrm{c}}$ superconductivity in this iron selenide material. In this material, the LiFeO${}_{2}$ layer is electrically neutral and does not act as an electron donor, which is remarkably different from other heavily electron-doped intercalated FeSe-derived superconductors. Based on our results and previous reports on FeSe-based superconductors, we figure out a $\mathsf{V}$-shaped anion height from the Fe layer dependence of ${T}_{\mathrm{c}}$ in the FeSe-derived superconductors, which is in contrast to the inverse $\mathsf{V}$-shaped one for the FeAs-based superconductors. Our studies expand the categories of the iron-based superconductors and open a door in the quest for potential superconductors with various spacer layers, which is helpful for the study of the underlying physics in iron-based high-${T}_{\mathrm{c}}$ superconductors.