Energetically Favored One-Dimensional Moiré Superstructure in the Pseudo-Square Lattice GdTe3

Abstract: Moir\'e engineering in layered crystals has recently gained considerable attention due to the discovery of various structural and physical phenomena, including interfacial reconstruction, superconductivity, magnetism, and distinctive optoelectronic properties. Nevertheless, most explored moir\'e systems have been limited to hexagonal lattices, thereby constraining a comprehensive understanding and technological application of moir\'e phenomena in general layered crystals. Here, we investigate GdTe3, a pseudo-tetragonal layered crystal, as a platform to explore unconventional moir\'e phenomena. GdTe3 exhibits a slight in-plane distortion correlated with the direction of charge density wave formation. Through vertical stacking of layers with different distortions-induced via a controlled strain/release process-we realize energetically favorable one-dimensional (1D) moir\'e superstructures. Using transmission electron microscopy (TEM), including high-resolution scanning TEM imaging, dark-field TEM imaging, and sample tilting experiments, we systematically examine stacking variations across the 1D moir\'e structure. Additionally, electron energy loss spectroscopy reveals modulations in electronic properties associated with the 1D moir\'e structure. Our findings expand the scope of moir\'e systems beyond conventional hexagonal twistronics, enabling exploration of moir\'e phenomena in low-symmetry van der Waals crystals.