  While it is well established that elevated temperatures can induce surface
roughening of metal surfaces, the effect of a high electric field on the atomic
structure at ambient temperature has not been investigated in detail. Here we
show with atomic resolution using in situ transmission electron microscopy how
intense electric fields induce reversible switching between perfect crystalline
and disordered phases of gold surfaces at room temperature. Ab initio molecular
dynamics simulations reveal that the mechanism behind the structural change can
be attributed to a vanishing energy cost in forming surface defects in high
electric fields. Our results demonstrate how surface processes can be directly
controlled at the atomic scale by an externally applied electric field, which
promotes an effective decoupling of the topmost surface layers from the
underlying bulk. This opens up opportunities for development of active
nanodevices in e.g. nanophotonics and field-effect transistor technology as
well as fundamental research in materials characterization and of yet
unexplored dynamically-controlled low-dimensional phases of matter.
