  Artificial spin ices (ASI) are arrays of single domain nano-magnetic islands,
arranged in geometries that give rise to frustrated magnetostatic interactions.
It is possible to reach their ground state via thermal annealing. We have made
square ASI using different FePd alloys to vary the magnetization via
co-sputtering. From a polarized state the samples were incrementally heated and
we measured the vertex population as a function of temperature using magnetic
force microscopy. For the higher magnetization FePd sample, we report an onset
of dynamics at $T = 493$ K, with a rapid collapse into $>90\%$ ground state
vertices. In contrast, the low magnetization sample started to fluctuate at
lower temperatures, $T = 393$ K and over a wider temperature range but only
reached a maximum of $25\%$ of ground state vertices. These results indicate
that the interaction strength, dynamic temperature range and pathways can be
finely tuned using a simple co-sputtering process. In addition we have compared
our experimental values of the blocking temperature to those predicted using
the simple N\'{e}el-Brown two-state model and find a large discrepancy which we
attribute to activation volumes much smaller than the island volume.
