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 Fe 3 O 4 arrays with unidirectional orientations on mica. The unidirectional alignment of nearly all the Fe 3 O 4 nanosheets is driven by a dual-coupling-guided growth mechanism. The Fe 3 O 4 /mica interlayer interaction induces two preferred antiparallel orientations, whereas the interisland interaction of Fe 3 O 4 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 Fe 3 O 4 . 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.