Title: Nanostructured complex oxides as a route towards thermal behavior in artificial spin ice systems,
Abstract: We have used soft x-ray photoemission electron microscopy to image the
magnetization of single domain La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ nano-islands
arranged in geometrically frustrated configurations such as square ice and
kagome ice geometries. Upon thermal randomization, ensembles of nano-islands
with strong inter-island magnetic coupling relax towards low-energy
configurations. Statistical analysis shows that the likelihood of ensembles
falling into low-energy configurations depends strongly on the annealing
temperature. Annealing to just below the Curie temperature of the ferromagnetic
film (T$_{C}$ = 338 K) allows for a much greater probability of achieving low
energy configurations as compared to annealing above the Curie temperature. At
this thermally active temperature of 325 K, the ensemble of ferromagnetic
nano-islands explore their energy landscape over time and eventually transition
to lower energy states as compared to the frozen-in configurations obtained
upon cooling from above the Curie temperature. Thus, this materials system
allows for a facile method to systematically study thermal evolution of
artificial spin ice arrays of nano-islands at temperatures modestly above room
temperature.