We present a theoretical investigation of the electronic and transport properties of magnetic zigzag (ZZ) graphene nanoflakes. In the ballistic regime, we identify transmission antiresonances as the clear fingerprint of destructive quantum interference (QI), in analogy with those observed in organic molecules such as benzene. The QI antiresonances are remarkably robust upon increasing the system size.
We show that, in the presence of short-range magnetic ordering, the interplay of QI and magnetism, results in spin-resolved QI features and in a nearly-perfect QI-assisted spin-filtering effect.
We demonstrate that upon breaking the graphene chiral sublattice symmetry, upon deposition of a suitable substrate, e.g., hexagonal BN, it is possible to achieve a direct electrostatic control over the spin polarization of the transport properties.
Hence, the unique combination of i) the extraordinary conduction properties of graphene, ii) QI effects, typical of molecular semiconductors, and iii) magnetic ordering, usually observed in bulk material, make graphene nanostructures with ZZ edges ideal candidates for the realization of high-performance spintronic devices.
A. Valli, A. Amaricci, A. Toschi, T. Saha-Dasgupta, K. Held, and M. Capone, Phys. Rev. B 94, 245146 (2016).
A. Valli, A. Amaricci, V. Brosco, and M. Capone, in preparation (2017).