Nov 23, 2010
Strain boosts self-organization of pits in manganite thin films
Structural strain, generated by substrate-film misfit, in combination with growth kinetic instabilities might promote the formation of self-organized arrays of pits in LSMO thin films. The formation of pit rows is guided by the steps of the regular step-terrace morphology of vicinal substrates in a narrow range of growth conditions. These mechanisms may hold generally for heteroepitaxial systems grown in kinetically limited conditions and may open a new way for the fabrication of long-range ordered nanostructures.
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.
About the author
The study was conducted by researchers from the Instituto de Ciencia de Materiales de Barcelona (ICMAB) and Centro de Investigación en Nanociencia y Nanotecnologia (CIN2) of CSIC. Dr Zorica Konstantinovic is a Ramon and Cajal researcher, interested in the formation of self-assembled nanostructures in oxide thin films. Dr Lluis Balcells, Dr José Santiso and Prof. Benjamin Martinez are senior staff researchers at CSIC. The current research interest of the group focuses on the preparation an characterization of complex oxide thin films and the exploration of potential applications in the design and development of electrical and magnetoelectronic devices.