Electric-field control of the degenerate shell in a triangular graphene quantum dot

Abstract For a triangular graphene quantum dot with up to two electrons filled in the degenerate shell, we calculate the eigenstates as functions of an electric field, using the tight-binding method, the Hartree-Fock method and the exact-diagonalization method. When the electric field is weaker, the eigenstates of the degenerate shell mix with each other. As the electric field becomes stronger, the eigenstates of the degenerate shell tend to be stable. We focus on the evolution of both the ground levels and the total spins in the electric field. Based on analyzing the chemical potentials, we present the control scheme of the shell filling and the total spin by the electric field. The results support the possibility to use the system as a spin memory device or an electron-transport switch.