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The study of the properties of boundaries between different materials—something that could one day change the world of electronics—is getting a boost from research being done by scientists in UT’s College of Engineering and Oak Ridge National Laboratory.

Gong Gu, an associate professor in the Department of Electrical Engineering and Computer Science, initiated a research effort to seamlessly join two two-dimensional crystals, earning a spot in the journal Science earlier this year.

“When you grow typical three-dimensional crystals on top of one another, the interface where they meet is, by default, two-dimensional,” said Gu. “That process is called heteroepitaxy. We’ve taken that a step further by joining a pair of two-dimensional crystals, which makes that boundary where they meet one-dimensional.”

These images taken from a high-powered microscope at Oak Ridge National Laboratory offer a first look at electrons along a one-dimensional boundary between graphene and hexagonal boron nitride.

The two materials, hexagonal boron nitride and graphene, have structures that line up nearly perfectly with one another—like an atomic zipper, in a sense.

Just as importantly, the electrons along the boundary are predicted to be “spin polarized,” meaning they prefer to all spin in the same direction.

This property is vital for applications in the emerging field of spintronics, which seeks to manipulate and use the spin of electrons to carry and process information, which may impact the future of all aspects of electronics.

Using scanning tunneling microscopy, ORNL’s An-Ping Li was able to provide the first look at electrons along the one-dimensional boundary.

“This work is just a stepping stone,” Gu said. “While the eventual outcome holds promise, the copper foil that the two crystals grow on destroys the spin polarization. The next big thing is to observe the spin polarization by stripping the copper away without harming the boundary.

UT postdoctoral student Lei Liu and student Ali Mohsin, both of the Department of Electrical Engineering and Computer Science, were on the overall team as well, as were members from ORNL and Central Methodist University.

The microscopy and simulation were conducted at the Center for Nanophase Materials Sciences at ORNL, with the junction grown at UT. The study is being published in Nature Communications, thanks to grants from the US Department of Energy, Defense Advanced Research Projects Agency, and the National Science Foundation.

C O N T A C T :

David Goddard (865-974-0683,