Grain boundaries in single-layer magnetic material CrCl3

Despite the crucial role that grain boundaries (GBs) play in the physical properties of crystalline materials, they have yet to be systematically studied for van der Waals magnetic monolayers. In this study, we investigated the epitaxial growth of monolayer CrCl3 and characterized the prevalent GB types in detail, identifying two dominant categories: those caused by grain rotation and those caused by grain sliding. Our structural and electronic analyses of these GBs revealed significant features associated with them. Notably, the findings include a generally enlarged bandgap at the boundaries and a 1D superstructure with twice the lattice constant at 0° GBs. Our work offers a microscopic perspective that serves as a foundation for understanding the macroscopic properties observed for practical 2D magnetic materials, especially those arising from crystalline imperfections.