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

Moiré 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 moiré systems have been limited to hexagonal lattices, thereby constraining a comprehensive understanding and technological application of moiré phenomena in general layered crystals. Here, we investigate GdTe₃, a pseudo-tetragonal layered crystal, as a platform to explore unconventional moiré 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) moiré 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 moiré structure. Additionally, electron energy loss spectroscopy reveals modulations in electronic properties associated with the 1D moiré structure. Our findings expand the scope of moiré systems beyond conventional hexagonal twistronics, enabling exploration of moiré phenomena in low-symmetry van der Waals crystals.