Electric-field-induced spin depolarization in graphene quantum dots

We study the effect of the in-plane electric field on the magnetic properties of charge-neutral triangular zigzag graphene quantum dot (GQD) by using the mean-field Hubbard Hamiltonian. Our calculated results show that spin depolarization begins to occur when the electric field is beyond some critical value. The spin-density distribution is more concentrated in the region of the GQDs with smaller electrostatic potential. This phenomenon is attributed to the competition between the many-body electron-electron interaction and the external electrostatic potential. Numerical results also show that the total spin of larger GQDs are easier to depolarize than the total spin of smaller GQDs. Moreover, the spin of GQDs with weak edge disorder still respond to an electric field but in a more irregular way. Our findings provide a path to electrically tuning the magnetic properties of GQDs.