Origin of half-semimetallicity induced at interfaces of C-BN heterostructures

Half-semimetallicity has been predicted to occur in zigzag-shaped graphene ribbons embedded in BN sheets. Using first-principles density-functional calculations a physical explanation is given, showing that the magnetism of the edge states in graphene strips and polarity effects in BN strips team up to give a spin asymmetric screening that induces an electronic reconstruction and half-semimetallicity at the interface, with a gap of at least a few hundreds of millielectron volts for one spin orientation and a tiny gap of tens of millielectron volts for the other. The dependence with ribbon widths is discussed, revealing that a range of ribbon widths is required to obtain the half-semimetallic state. These results prove that unconventional physical effects similar to those observed at insulating oxide interfaces, can also exist in lower dimensions, opening alternative routes for tuning electronic properties at nanointerfaces.