Researchers at the Instituto de Ciencia de Materiales de Barcelona (ICMAB-CSIC) are studying complex oxide thin films and heterostructures intended for magnetoelectronic applications. In this particular study, manganite thin films were grown by RF magnetron sputtering in a variety of substrates giving different structural strain.

It was observed that well defined pits form in coherently grown films at a low misfit independently of its sign (tensile or compressive stress) in a very narrow growing-rate range. However, the pit volume scales inversely with the lattice mismatch.

In addition, it was observed that the formation of pits was strongly correlated with the terrace-step surface morphology of the underlying vicinal substrates. The pit rows align along the step edges.

Although strain alone cannot explain the appearance of pits, it appears to be a key tool for tailoring the size and arrangement of pits in concomitance with the terrace-step morphology of the substrate. In the next phase of their work, the researchers are interested in using these self-organized morphologies as templates for directed self-assembly of nanoparticles.

The team presented its work in the journal Nanotechnology.