Superconductivity in LiFeO2Fe2Se2 with anti-PbO-type spacer layers

We report on a superconductor LiFeO2Fe2Se2 with T-c similar to 43 K, synthesized via the hydrothermal method. The anti-PbO-type spacer layer of LiFeO2 has been successfully intercalated between the anti-PbO-type FeSe layer, which results in a high-T-c superconductivity in this iron selenide material. In this material, the LiFeO2 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 V-shaped anion height from the Fe layer dependence of T-c in the FeSe-derived superconductors, which is in contrast to the inverse 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-c superconductors.