Atom-by-atom imaging of moiré transformations in 2D transition metal dichalcogenides.

Understanding the atomic-scale mechanisms that govern the structure of interfaces is critical across materials systems but particularly so for two-dimensional (2D) moiré materials. Here, we image, atom-by-atom, the thermally induced structural evolution of twisted bilayer transition metal dichalcogenides using in situ transmission electron microscopy. We observe low-temperature, local conversion of moiré superlattice into nanoscale aligned domains.

Bend-Induced Ferroelectric Domain Walls in α-InSe.

The low bending stiffness of atomic membranes from van der Waals ferroelectrics such as α-InSe allow access to a regime of strong coupling between electrical polarization and mechanical deformation at extremely high strain gradients and nanoscale curvatures. Here, we investigate the atomic structure and polarization at bends in multilayer α-InSe at high curvatures down to 0.3 nm utilizing atomic-resolution scanning transmission electron microscopy, density functional theory, and piezoelectric force microscopy.

In Situ Imaging of an Anisotropic Layer-by-Layer Phase Transition in Few-Layer MoTe.

Understanding the phase transition mechanisms in two-dimensional (2D) materials is a key to precisely tailor their properties at the nanoscale. Molybdenum ditelluride (MoTe) exhibits multiple phases at room temperature, making it a promising candidate for phase-change applications. Here, we fabricate lateral 2- interfaces with laser irradiation and probe their phase transitions from micro- to atomic scales with heating in the transmission electron microscope (TEM).