  Previously, graphene nanoribbons set in lateral heterostructures with
hexagonal boron nitride were predicted to support topologically protected
states at low energy. We investigate how robust the transport properties of
these states are against lattice disorder. We find that forms of disorder that
do not couple the two valleys of the zigzag graphene nanoribbon do not impact
the transport properties at low bias, indicating that these lateral
heterostructures are very promising candidates for chip-scale conducting
interconnects. Forms of disorder that do couple the two valleys, such as
vacancies in the graphene ribbon, or substantial inclusions of armchair edges
at the graphene-hexagonal boron nitride interface will negatively affect the
transport. However, these forms of disorder are not commonly seen in current
experiments.
