Magnetic and Electric Properties of a Grain Boundary in Single-Layer CrI₃

Single-layer CrI₃ has attracted considerable interest because of its 2D magnetism. However, the properties of defects in single-layer CrI₃ have not been thoroughly studied yet. In this study, a line defect in the CrI₃ single layer, which is a grain boundary caused by the position flipping of iodine atoms, is theoretically investigated. Using first-principles calculations, the structural and electronic properties of this grain boundary in both zigzag and armchair directions are explored. The grain boundary exhibits ferromagnetic exchange interaction between the two grains. The conduction band minimum and valence band maximum of the grain boundary states are in the energy gap of perfect CrI₃ single layer and form a direct gap, indicating an enhancement in photoelectronic properties. Moreover, the partial charge density in real space reveals that the doped electrons or holes predominantly distribute at the grain boundary. This can support a purely spin-polarized current along the grain boundary. Findings suggest that the grain boundary exhibits unique electronic and magnetic properties, potentially offering valuable insights for spintronics applications.