Numerical calculation of the quantum Hall effect in the1T-TaS2lattice

The material1T-TaS2with the charge density wave phase can be employed to achieve multiple robust flat bands that depends on the number (m) of extra atoms residing on each edge of the hexagon (Leeet al2020Phys. Rev. Lett.124137002). Whenm = 1, the1T-TaS2lattice represents the line-centered honeycomb lattice. We report a theoretical study of the integer quantum Hall effect (IQHE) in the honeycomb superlattice model from the nearly commensurate charge-density-wave phase of1T-TaS2which has a flat band at band center crossing a single Dirac cone. It is shown that the Dirac electrons exhibit a conventional nonrelativistic IQHE ofσxy=ve2/h(v=0,±2,±4,…)while a zero Hall platform grows at the band center from the electrons of the flat band. The zero-Hall platform can be easily destroyed by the disorder effect due to the band broadening effect. The staggered potential controlled by an external electric field is introduced into the system to open an energy gap and an emergent IQHE is observed in the band gap. The relativistic half-IQHE is also found in the system in the energy region nearKandK' valleys far away from the band center.