We used the first principle of density functional theory to perform detailed calculations regarding the structure, and the electronic and magnetic properties of MX (M[Formula: see text]=[Formula: see text]Ga, In; X[Formula: see text]=[Formula: see text]S, Se, Te) nanoribbons. The armchair nanoribbons (ARNs) are nonmagnetic semiconductors, which have even or odd oscillations of bandgaps. All small-sized zigzag nanoribbons (ZRNs) were found to break the six-membered ring structure and move to the center, thereby exhibiting nonmagnetic semiconductor behavior owing to the quantum confinement effect. However, among the large ZRNs, which are all metals, MTe ZRNs are nonmagnetic; this differs from the case of graphene, MoS2 and Ti2CO2 nanoribbons. MX (M[Formula: see text]=[Formula: see text]Ga, In; X[Formula: see text]=[Formula: see text]S, Se) ZRNs exhibited ferromagnetism owing to the presence of the unpaired electrons on the metal-edge side and the magnetic moment of each pair of molecules, which was controlled by the size of the nanoribbons. The results provided a theoretical reference that can be used in the future to produce MX materials for application in low-dimensional semiconductor devices, spin electron transport devices and new magnetoresistance devices.
