  Structural superlubricity is a special frictionless contact in which two
crystals are in incommensurate arrangement such that relative in-plane
translation is associated with vanishing energy barrier crossing. So far, it
has been realized in multilayer graphene and other van der Waals
two-dimensional crystals with hexagonal or triangular crystalline symmetries,
leading to isotropic frictionless contacts. Directional structural
superlubricity, to date unrealized in two-dimensional systems, is possible when
the reciprocal lattices of the two crystals coincide in one direction only.
Here, we evidence directional structural superlubricity a
$\alpha$-bismuthene/graphite van der Waals system, manifested by spontaneous
hopping of the islands over hundreds of nanometres at room temperature,
resolved by low-energy electron microscopy and supported by registry
simulations. Statistical analysis of individual and collective
$\alpha$-bismuthene islands populations reveal a heavy-tailed distribution of
the hopping lengths and sticking times indicative of L{\'e}vy flight dynamics,
largely unobserved in condensed-matter systems.
