Sliding‐Induced Out‐of‐Plane Ferroelectricity of 2D MnPS3

The emerging 2D transition metal thiophosphites with multiferroicity show great potential in new‐concept and multifunctional nanoelectronics for neuromorphic technologies. Although extensive research has focused on the symmetry‐breaking structures and induced low‐temperature ferroic orders of 2D MnPS3, its room‐temperature ferroic behaviors are still elusive. In this work, we reveal the out‐of‐plane ferroelectricity as well as the first room‐temperature ferroic order of 2D MnPS3. The observation of interlayer displacements and surface potential differences in 2D MnPS3 evidences that its unpredicted ferroelectric polarization stems from sliding‐induced symmetry breaking. In addition, we combine 2D MnPS3 as the dielectric layer and a WSe2 channel to construct a van der Waals ferroelectric field‐effect transistor, which shows bipolar memory characteristics with an on/off ratio of 104 at ambient and cryogenic circumstances. This work uncovers the out‐of‐plane ferroelectricity of 2D MnPS3, paving the way to fabricate ferroelectronic devices with multi‐functionality.