Antichiral edge states in diatomic square lattice and quantum transport properties

We investigate the energy spectrum and transport properties of a diatomic square lattice model that manifest antichiral characteristics. The emergence of antichiral edge states is primarily governed by the relative sign of the next-nearest-neighbor hopping parameters on the two sublattices. However, in finite systems, the atomic structure at the boundaries plays a crucial role in determining whether the system exhibits chiral/antichiral behavior. Using both analytical and numerical methods, we reveal the presence of antichiral edge states in ribbon geometries and emphasize the importance of atomic connectivity at the edges. Extending our analysis, we simulate various finite size geometries to identify which configuration supports antichiral behavior. The transport properties are studied in the Landauer-B"uttiker approach for a Hall device with four leads. We study the transmittance coefficients, transverse (Hall), and longitudinal resistance by comparing the antichiral versus chiral situations. In particular, the antichiral case shows a vanishing Hall effect and negative longitudinal resistance. The presence of the bulk currents is proved by calculating explicitly the currents on the plaquette and the local density of states in the system with leads. Additionally, we investigate the influence of Anderson disorder on the transmittance coefficients to highlight the reduced robustness of antichiral systems.