  Tailor-made magnetic nanostructures offer a variety of functionalities useful
for technological applications. In this work, we explore the possibilities of
realizing Fe nanostructures at the interfaces of 2D graphene and h-BN by ab
initio density functional calculations. With the aid of ab initio
Born-Oppenheimer molecular dynamics simulations and diffusion barriers
calculated by nudged elastic band method, we find that (i) diffusion barriers
of Fe on BN are much smaller than those on graphene, (ii) the Fe adatoms form
clusters within a short time interval (~2.1 ps) and (iii) Fe clusters diffuse
easily across the C-N interface but become immobile at the C-B interface. The
calculated magnetic exchange coupling between Fe clusters at C-B interfaces
varies non-monotonically as a function of the width of BN separating the
graphene parts. One may envisage design of magnetic nanostructures at the C-B
interface of 2D graphene/h-BN hybrids to realize interesting applications
related to spintronics.
