Creating Astonishing Properties in Oxide Nanosandwiches
Darrell G. Schlom
Department of Materials Science and Engineering and
Kavli Institute at Cornell for Nanoscale Science
Cornell University, Ithaca,USA
Thin-film synthesis has played a critical role in the development of conventional semiconductor devices, as well as in shaping the current landscape of fundamental science and technology at the nanoscale. Techniques like molecular-beam epitaxy, which is famous for its ability to customize the layering of semiconductors with atomic-layer precision, can also be applied to the growth of thin films of multicomponent oxide materials. With their wider assortment of functional properties, creating oxide nanosandwiches and applying thin film tricks to enhance their properties has tremendous potential. Using epitaxy and the misfit strain imposed by an underlying substrate, it is possible to strain oxide thin films to percent levels—far beyond where they would crack or plastically deform in bulk. Under such strains, the properties of oxides can be dramatically altered. For example, materials that are not ferroelectric or ferromagnetic in their unstrained state can be transmuted into ferroelectrics, ferromagnets, or materials that are both at the same time. Results of fundamental scientific importance as well as revealing the tremendous potential of utilizing multicomponent oxide thin films to create devices with enhanced performance will be shown.