Extended Data Figure 10 : Calculated stable structures for LuFe2O4 and the (LuFeO3)3/(LuFe2O4)1 superlattice.

From: Atomically engineered ferroic layers yield a room-temperature magnetoelectric multiferroic

Extended Data Figure 10

Monoclinic structures of the LuFe2O4 system containing charge-ordered Fe2+/Fe3+. a, The antiferroelectric charge-ordered state (COI); b, the ferroelectric charge-ordered state (COII); and c, the non-polar charge-ordered state (COIII). Panels a and b are shown in Fig. 3a and b, respectively. df, Single-domain (d) and undoped-type (e) and doped-type structures of the (LuFeO3)3/(LuFe2O4)1 structure. Electrons transfer from the LuFe2O4 layers to the LuFeO3 layers in the doped-type configuration (orange arrows). The doped-type configuration also stabilizes charged ferroelectric domain walls. The density of states for the Fe3+ and Fe2+ ions are plotted in f in yellow and green, respectively. Lutetium, Fe3+, Fe2+ and oxygen are shown in turquoise or red (depending on the ferroelectric polarization), yellow, green and brown, respectively.