In-plane electric and exchange fields engineered corner state bismuthene quantum dots

Abstract

The energy spectrum of bismuthene quantum dots in the presence of in-plane electric and exchange fields are investigated by the tight-binding method. In the case of an in-plane exchange field, bismuthine is a second-order topological insulator and supports corner states in triangular and hexagonal quantum dots with zigzag edges. The corner states in hexagonal bismuthene quantum dots are more stable than the corner states in triangular quantum dots. In hexagonal quantum dots, the corner states are degenerate at zero energy as the exchange field h > 0.18 eV. However, the degeneracy of corner states can be destroyed by the electrical fields, and the energy levels of corner states oscillate with respect to the electric field direction. In addition, the on-site disorders will not destroy the corner states but lead to the separation of these states around zero energy.