  We report a study of demagnetization protocols for frustrated arrays of
interacting single domain permalloy nanomagnets by rotating the arrays in a
changing magnetic field. The most effective demagnetization is achieved by not
only stepping the field strength down while the sample is rotating, but by
combining each field step with an alternation in the field direction. By
contrast, linearly decreasing the field strength or stepping the field down
without alternating the field direction leaves the arrays with a larger
remanent magnetic moment. These results suggest that non-monotonic variations
in field magnitude around and below the coercive field are important for the
demagnetization process.
