Tuning topologically nontrivial states in the BHT-Ni metal organic framework

Abstract

Using first principles calculations, we have demonstrated the creation of multiple quantum states, in the experimentally accessible metal organic framework BHT-Ni. Specifically, quantum spin Hall and quantum anomalous Hall states are induced by two and four electron doping, respectively. The geometrical symmetry breaking, is also investigated. For a low electron doping concentration of two electrons per unit cell, the Fermi energy shifts to a nontrivial band gap, between Dirac bands and a quantized spin Hall conductivity is predicted. Subsequently in a high electron doping concentration, Anomalous Hall conductivity with a quantized value was observed. In addition, for centrosymmetric (trans-like) and non-centrosymmetric (cis-like) structures, we found that the trans-like structure preserves quantum spin Hall and quantized spin Hall conductivity. In contrast, in the cis-like structure, space inversion symmetry breaking leads to the appearance of valley Hall effect and the disappearance of spin Hall conductivity.