Faster circuits with superhero electrons?

PRINCETON (US)—On a quest to discover new states of matter, a team of scientists has found that electrons on the surface of specific materials act like miniature superheroes.

They’re relentlessly dodging the cliff-like obstacles of imperfect microsurfaces, sometimes moving straight through barriers.

The work represents the first time such behavior of electrons has been tracked and recorded, and hints at the possibilities of speeding up integrated circuits that process information by flow of electrons between different devices.

The new materials potentially could break the bottleneck that occurs when metallic interconnects get so small that even the tiniest atomic imperfection hinders their performance.

Princeton University physics professor Ali Yazdani and his team observed the extraordinary physics behavior in a “topological surface state” on a microscopic wedge of the metal antimony. The work is reported in the July 15 issue of Nature.

Normally, electron flow in materials is impeded by imperfections—seemingly slight edges and rifts act like cliffs and crevasses in this microscopic world, blocking electrons in their path.

Recent theories, however, predict that electrons on the surface of some compounds containing elements such as antimony can be immune to such disruptions in their flow. The connectivity in their flow, Yazdani says, stems from a special form of electron wave that seemingly alters the pattern of flow around any imperfection.

Many of the “topological” materials, such as antimony, have been important in the world economy; however, their unusual surface conduction previously had not been examined.

Part of the challenge had been the difficulty in measuring the flow of electrons just at the surface, a task that was accomplished by the Princeton group using a specialized microscopy technique that enables precise visualization of electrons at the surface of materials.

“Material imperfections just cannot trap these surface electrons,” says Yazdani. “This demonstration suggests that surface conduction in these compounds may be useful for high-current transmission even in the presence of atomic scale irregularities—an electronic feature sought to efficiently interconnect nanoscale devices.”

The research primarily was funded by the National Science Foundation. In addition, the U.S. Army Research Office, the Office of Naval Research, the U.S. Department of Energy, and the W. M. Keck Foundation contributed through support of the instrumentation and infrastructure at the Princeton Nanoscale Microscopy Laboratory.

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