  Frustrated systems, typically characterized by competing interactions that
cannot all be simultaneously satisfied, display rich behaviours not found
elsewhere in nature. Artificial spin ice takes a materials-by-design approach
to studying frustration, where lithographically patterned bar magnets mimic the
frustrated interactions in real materials but are also amenable to direct
characterization. Here, we introduce controlled topological defects into square
artificial spin ice lattices in the form of lattice edge dislocations and
directly observe the resulting spin configurations. We find the presence of a
topological defect produces extended frustration within the system caused by a
domain wall with indeterminate configuration. Away from the dislocation, the
magnets are locally unfrustrated, but frustration of the lattice persists due
to its topology. Our results demonstrate the non-trivial nature of topological
defects in a new context, with implications for many real systems in which a
typical density of dislocations could fully frustrate a canonically
unfrustrated system.
