Torsional force microscopy of van der Waals moirés and atomic lattices

Significance Moiré superlattices, formed by superimposing two layers of graphene or other two-dimensional (2D) materials at a relative twist angle, have been studied extensively, but techniques to directly image the moirés at room temperature and in air remain scarce. Here, we introduce torsional force microscopy (TFM), an AFM-based technique, that reveals moirés formed in atomically thin materials. We find that TFM also reveals atomic crystal lattices of these materials. TFM can be used to image 2D materials on polymer stamps, without the need for any electrical contacts, providing an unprecedented preview of structural properties of moiré heterostructures before, during, and after stacking.