University of Pittsburgh
March 2, 2008

Inspired by Etch A SketchTM Toy, Pitt-Led Team Invents Technique for Switching Electrical Properties at Nanometric Scales

Metallic features can be written and erased at scales that approach atomic dimensions, with wide-ranging potential for information technologies, as reported online in "Nature Materials"
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PITTSBURGH-A University of Pittsburgh-led research team developed a process wherein the ability to conduct electricity can be turned on and off at nanoscale dimensions. This capability holds promise for more powerful and compact information technologies including ultra-high density information storage, reconfigurable logic devices, single-electron devices, and quantum computers. These findings were published online March 2 in "Nature Materials" with the print version scheduled for April.

Led by Jeremy Levy, a professor of Physics and Astronomy in Pitt's School of Arts and Sciences, the researchers discovered how to switch, at will, the interface of two readily formed insulating materials from an electrical conductor to an insulator and back. The research's considerable technological applications stem from this adjustability, Levy said.

The process works like a microscopic Etch A SketchTM, Levy explained, referencing the drawing toy of his youth that inspired his idea. The interface lies between a crystal of strontium titanate and a 1.2 nanometer-thick layer of lanthanum aluminate, both of which are insulators. Using the sharp conducting probe of an atomic-force microscope, the team created wires less than 4 nanometers wide at the interface of the two materials. These conducting nanostructures can subsequently be erased with a reverse voltage or with light, rendering the interface an insulator once more.

"This work is not only potentially useful for technological applications, but also fascinating from a fundamental perspective," Levy said. "The prospect of making both logic and memory devices with the same material is very intriguing, and at this small of a scale, it's almost unheard of."

The physical model still needs tested in crucial ways, but provides an important framework for future research directions, Levy said. For example, the interface also acted as a transistor-an essential part of electronic devices that regulates electron flow-when the atomic-force probe served as a gate; further research will include creating devices that utilize single electrons for logic or storage.

The idea originated from a visit Levy made to the University of Augsburg in Germany where coauthors Jochen Mannhart and his student Stefan Thiel showed Levy how the entire interface could be switched between a conducting and insulating state. Levy thought of adapting the process to nanoscale dimensions and his student, Cheng Cen, the paper's first author, brought the idea to fruition. Research by C. Stephen Hellberg from the Naval Research Laboratory contributed to the theoretical understanding of the project. The work was supported by the Defense Advanced Research Projects Agency and the National Science Foundation.

Levy has worked in the field of oxide electronics for the last decade, and has been recognized by Pitt with the Chancellor's Distinguished Teaching Award in 2007 and the Chancellor's Distinguished Research Award in 2004.




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