Researchers at the University of Minnesota, Twin Cities have demonstrated an unexpected new way to change the electronic behavior of metals. By carefully engineering the atomic interactions where the two materials meet, the team was able to significantly change the properties of the metallic material.
The survey results are nature communicationsshow that the surface work function of metallic ruthenium dioxide (RuO2) can be tuned by more than 1 electron volt (eV) using a phenomenon known as interfacial polarization. The effect was obtained by changing the thickness of the ultrathin film by just a few nanometers.
Atomic scale control of metal properties
Polarization is usually associated with insulating materials and ferroelectrics rather than metals. However, researchers have discovered a way to stabilize polarization within metal systems and use it to influence the behavior of electrons.
“Polarization is often thought of as belonging to insulators and ferroelectrics, not metals,” says Bharat Jalan, Shell Professor and Professor in the Department of Chemical Engineering and Materials Science at the University of Minnesota. “Our work shows that by carefully designing the interface, we can stabilize the polarization of a metallic system and use it as a knob to tune its electronic properties. This opens up entirely new ways of thinking about the control of metals.”
The research team found that the effect was highly dependent on the thickness of the metal layer. The most dramatic change occurred when the ruthenium dioxide film reached a thickness of about 4 nanometers, or the width of a single DNA strand.
Significant transition at 4 nanometers
At this thickness, the metal transitions from a strained state caused by the underlying material to a more relaxed atomic arrangement. This result provides direct evidence that the way atoms are organized within a material can have a measurable impact on its electronic properties.
“This was a surprise,” said Seung Gyo Jeong, lead author of the study and a researcher at the Jalan Group. “We were expecting subtle interfacial effects, but not such large and controllable changes in the work function. It was particularly exciting to be able to visualize polar displacements at the atomic scale and link them directly to electronic measurements.”
By observing the movement of small atoms and coupling it with large electronic changes, the researchers were able to show how interfacial engineering can be used as a powerful tool to control metals.
Potential applications in electronics and quantum technology
The discovery not only advances scientists’ understanding of fundamental physics, but could also guide the development of future electronic devices, catalytic systems, and quantum technologies.
The research included collaborators from the University of Minnesota Twin Cities, Massachusetts Institute of Technology, Texas A&M University, Gwangju University of Science and Technology, and the Department of Physics at the University of Minnesota Twin Cities.
Funding for this research was provided by the U.S. Department of Energy and the Air Force Office of Scientific Research.
