Effect of off-center positively charged Coulomb impurity on Dirac states in graphene magnetic dot

• Spectra of magnetic dot bound to positively charged impurity are considered.
• The problem is solved by numerical diagonalization.
• The electron–hole symmetry is broken by the Coulomb potential.
• Zero energy states become nondegenerate and split into hole-like states.
• Level orderings are reversed in the hole states at critical magnetic fields.

Using numerical diagonalization, we study the effect of the position of an off-center positively charged Coulomb impurity in a graphene magnetic dot, whose magnetic field profile is chosen as a Gaussian type. Numerical results show that the electron–hole symmetry is broken by the Coulomb potential and the originally zero energy states become nondegenerate and split into hole-like states. For the higher Landau levels shown, owing to the competition between the repulsive Coulomb potential and the magnetic confinement, the level orderings are reversed in the hole states at critical magnetic fields. Similar results are also obtained in the dot-size dependence of the low-lying spectra.