By paying close attention to how two materials behave when a single layer of atoms touch, a Cornell physicist's research could potentially lead to simpler, less costly electronic devices.

David A. Muller, Cornell professor of applied and engineering physics, has shown how some interfaces can be manipulated to remain stable by moving only single layers of atoms. His research shows that two particular oxides, lanthanum aluminate and strontium titanate, are good examples of this ability.

"One of the things we're trying to do when miniaturizing electronics is to really shrink things to the atomic scale," Muller explained. "You have to control the material at the atomic scale to get a perfect interface. And if you don't, you'll notice it in the properties of the system you're trying to make."

The results of Muller's research, in collaboration with Naoyuki Nakagawa and Harold Y. Hwang of the University of Tokyo, appeared in the March 2006 issue of Nature Materials. The paper recently was chosen by the journal as one of its "Top 10" papers of 2006.

A commentary piece by Knut Urban of the Institute for Solid State Research calls the collaborative research "a landmark in modern quantitative atomic-resolution electron microscopy."

Using a scanning transmission electron microscope, the scientists studied the interfaces between lanthanum aluminate films grown on strontium titanate crystals. They showed that by changing only the final layer of atoms in either material, before it touched the next material, the properties could be changed, making the materials either insulating or conducting.

"We think we know how to improve the performance of devices made from these materials, because you need to switch the interface termination in order to get a good device," Muller explained.

Muller and his colleagues have long studied oxides for increasing the functionality of silicon or other conventional materials for semiconductors.

Oxides could prove useful in the electronics world, whether as memory storage devices, filters or surge protectors for cell phones, because of their ability to display many different properties. The challenge scientists face, Muller said, is to make the materials as defect-free and as high-quality as semiconductors used in electronics today.