Interisland-Distance-Mediated Growth of Centimeter-Scale Two-Dimensional Magnetic Fe 3 O 4 Arrays with Unidirectional Domain Orientations.

Two-dimensional (2D) nanosheet arrays with unidirectional orientations are of great significance for synthesizing wafer-scale single crystals. Although great efforts have been devoted, the growth of atomically thin magnetic nanosheet arrays and single crystals is still unaddressed. Here we design an interisland-distance-mediated chemical vapor deposition strategy to synthesize centimeter-scale atomically thin FeO arrays with unidirectional orientations on mica. The unidirectional alignment of nearly all the FeO nanosheets is driven by a dual-coupling-guided growth mechanism. The FeO/mica interlayer interaction induces two preferred antiparallel orientations, whereas the interisland interaction of FeO breaks the energy degeneracy of antiparallel orientations. The room-temperature long-range ferrimagnetic order and thickness-tunable magnetic domain evolution are uncovered in atomically thin FeO. This strategy to tune the orientations of nanosheets through the an interisland interaction can guide the synthesis of other 2D transition-metal oxides, thereby laying a solid foundation for future spintronic device applications at the integration level.