Width- and Edge-Dependent Stability, Electronic Structures, and Magnetic Properties of Graphene-Like and Wurtzite ZnS Nanoribbons

First principles methods within the generalized gradient approximation (GGA) and GGA + U were used to investigate the stability and electronic and magnetic properties of graphene-like (terminated with zigzag or armchair edges) and wurtzite ZnS nanoribbons. In the zigzag graphene-like nanoribbons (Z-GNRs), the ferromagnetic and metallic behaviors are independent of the ribbon width. In contrast, the armchair graphene-like nanoribbons (A-GNRs) are nonmagnetic semiconductors. Wurtzite ZnS nanoribbons (W-NRs) exhibit the ferromagnetic and semiconducting features. All of the A-GNRs have direct band gaps, which decrease gradually with the increase of the ribbon width. The majority spin channels in W-NRs gradually changed from the indirect (when the width N-z is within 5-7) to direct band gaps (8 <= N-z <= 10). All of the minority spin channels have direct band gaps. The magnetizms of Z-GNRs and W-NRs decrease gradually with the increase of the NRs width. The binding energies increase monotonically with increasing ribbon widths for zigzag and armchair ZnS GNRs and wurtzite ZnS NRs. With similar widths, the stability order of three types of NRs is as follows: W-NRs > A-GNRs > Z-GNRs. The metal-free metallicity predicted for narrow Z-GNRs may be useful in nanomaterial-based spintronics applications.