Zero energy states oriented tunability of spin polarization in zigzag-edged bowtie-shaped graphene nanoflake by electric field.

A comprehensive first-principles study of the correlation between the zero energy states and the tunability of the spin-selective semiconducting properties of zigzag-edged bowtie-shaped graphene nanoflakes (ZBGNFs) under electric field is presented for the first time. We demonstrate that the spin degenerate semiconducting ground state can be lifted by electric field. In particular, we find that the nullity defined by structural configuration determines the complexity and efficiency of the tunability of spin polarization. In origin, fine-tuning spin dependent properties by electric field is the manipulation on spin-polarized molecular orbitals energies. We expect this study to help design low-dimensional molecular spintronics more effectively and controllably.