Coexistence of Ferroelectricity and Ferromagnetism in Atomically Thin Two-Dimensional CrS/WS Vertical Heterostructures.

Two-dimensional (2D) heterostructures with ferromagnetism and ferroelectricity provide a promising avenue to miniaturize the device size, increase computational power, and reduce energy consumption. However, the direct synthesis of such eye-catching heterostructures has yet to be realized up to now. Here, we design a two-step chemical vapor deposition strategy to growth of CrS/WS vertical heterostructures with atomically sharp and clean interfaces on sapphire. The interlayer charge transfer and periodic moiré superlattice result in the emergence of room-temperature ferroelectricity in atomically thin CrS/WS vertical heterostructures. In parallel, long-range ferromagnetic order is discovered in 2D CrS via the magneto-optical Kerr effect technique with the Curie temperature approaching 170 K. The charge distribution variation induced by the moiré superlattice changes the ferromagnetic coupling strength and enhances the Curie temperature. The coexistence of ferroelectricity and ferromagnetism in 2D CrS/WS vertical heterostructures provides a cornerstone for the further design of logic-in-memory devices to build new computing architectures.