Defect-Free and Tailored Spin States for Thin Films
Thin films are used in many technologies from semiconductor fabrication to nanotechnology, and will eventually be used in solar cells and fuel cells. Before they can spread to these other technologies though, the defects from their production have to be removed. Luckily researchers at Oak Ridge National Laboratory (ORNL) have found a way to grow thin films without any defects, and discovered how to create stripes of certain spin states in the crystalline structure.
Epitaxial thin films are produced by having the thin film grow on top of a different material. The atoms of the thin film align themselves with the crystal structure of the substrate, but this can create stress in the thin film which degrades its quality. The researchers analyzed how cobaltite thin films relax from different strain states and were surprised to find stripes form in the crystal structure, where the atoms aligned their spins. Potentially this result could be used to control the growth of the thin films to prevent defects from occurring, and giving the films specific magnetic properties.
Even though this was only discovered for cobaltite thin films, this is still an important finding. Cobaltite films are good candidates for magnetic sensors, ionic conductors, and surface catalysts, so even if this manipulation is not possible with other thin films, it will not be wasted.