Two-dimensional Dirac semimetals with tunable edge states

We theoretically propose a design for two-dimensional Dirac semimetals using a bilayer-modified Bernevig-Hughes-Zhang (BHZ) model. By introducing new sites into the BHZ model, we engineer flat bands at the Fermi energy. In the bilayer system, interlayer coupling separates these flat bands, resulting in two Dirac points that preserve time-reversal and inversion symmetries. Two Dirac points are connected by a one-dimensional Fermi arc edge state, whose bound nature is confirmed by quantized transmission resonance peaks. Notably, the position of the Dirac points can be precisely tuned by adjusting interlayer coupling strengths and symmetries.