Half-metallic graphene nanoribbons

We show that this phenomenon is realizable if in-plane homogeneous electric fields are applied across the zigzag-shaped edges of the graphene nanoribbons, and that their magnetic property can be controlled by the external electric fields

Young-Woo Son

2006

Scholarcy highlights

  • Electrical current can be completely spin polarized in a class of materials known as half-metals, as a result of the coexistence of metallic nature for electrons with one spin orientation and insulating for electrons with the other
  • Such asymmetric electronic states for the different spins have been predicted for some ferromagnetic metals−for example, the Heusler compounds1−and were first observed in a manganese perovskite
  • We predict halfmetallicity in nanometre-scale graphene ribbons by using first-principles calculations. We show that this phenomenon is realizable if in-plane homogeneous electric fields are applied across the zigzag-shaped edges of the graphene nanoribbons, and that their magnetic property can be controlled by the external electric fields
  • When a single graphite layer is terminated by zigzag edges on both sides, which we refer here to as a zigzag graphene nanoribbon, there are peculiar localized electronic states at each edge
  • We find that the ground state of the ZGNRs, including spin degree of freedom, has a bandgap which is inversely proportional to the ribbon width
  • With applied transverse electric fields, we find that the valence and conduction edge-state bands associated with one spin orientation close their gap, whereas those associated with the other widen theirs
  • Under these conditions, the half-metallic nature is robust even though a transverse electric fields is applied, and spin polarized current should be obtained in transport experiment with split-gates

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