Center for Functional Nanomaterials Seminar

Studies of hybrid C/BN heterostructures have experienced a considerable thrust after the spectacular rise of graphene and its applications, and the recent fabrication of BN monolayers(1). Synthesis of C/BN nanotubes(2) and nanosheets(3) have already been reported. These hybrid nanostructures offer a unique route for material engineering, by combination of the exciting properties of graphene with those of insulating polar BN. Here, I will present first principles (DFT) calculations of the zigzag-terminated interfaces between C and BN nanodomains, proving that unconventional physical effects similar to those observed at insulating oxide interfaces(4), can also exist in lower dimensions, opening alternative routes for tuning electronic properties at nanointerfaces. It will be shown that the magnetic character of the edge states in zigzag shaped graphene nanoribbons, and the polar BN edge, team up to give a spin asymmetric screening that induces half-semimetallicity at the interface, with a gap of a few tenths of eV for one spin orientation, and a tiny gap of hundredths of eV for the other(5). This effect is also observed in tubular geometries, as long as the interface is zigzag-edged.

References:

(1) Pacile et. al. Appl. Phys. Lett. 2008, 92, 133107; Jin et. al. Phys. Rev. Lett. 2009, 102, 195505.
(2) Suenaga et. al. Science 1997, 278, 5338; Enouz et. al. Nano Lett. 2007, 7, 1856.
(3) Ci et. al. Nat. Materials 2010, 9, 430.
(4) Ohtomo & Hwang Nature 2004, 427, 423; Brinkman et. al. Nat. Mater. 2007, 6, 493; Reyren et. al. Science 2007, 317, 5842.
(5) Pruneda Phys. Rev. B 2010, 81, 161409(R)