![]() The multiple layers built a crystal “superlattice.” Its cells were identical except for the elements at their centers. They added two layers of lanthanum ferrite (LaFeO 3) followed by one layer of strontium ferrite (SrFeO 3), and repeated the process to produce a film a few billionths of a meter in thickness. To create complex oxides, the scientists coated a substrate atomic layer by atomic layer. Those small defect-driven shifts have big consequences for the physical properties of materials that hold promise for storing and manipulating data and sensing magnetic fields. The study showed oxygen atoms occupied parts of the lattice but vacated others, causing iron atoms to shift. Defects are often detrimental to material properties, but these findings show they can provide a new mechanism for manipulating electricity, magnetism and other behaviors important for energy and information technologies. The study’s biggest surprise, however, was how material defects induced the polar behavior. ![]() “Two plus two doesn’t always equal four,” said project leader Albina Borisevich. This makes polar materials useful for devices such as sensors and actuators. The charge asymmetry creates an extra “switch” that brings new functionalities to materials when “flipped” by external stimuli such as electric fields or mechanical strain. Although each layer had an intrinsically nonpolar (symmetric) distribution of electrical charges, the lattice had an asymmetric distribution of charges. AugResearchers at the Department of Energy’s Oak Ridge National Laboratory got a surprise when they built a highly ordered lattice by layering thin films containing lanthanum, strontium, oxygen and iron. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |