Materials team explores electron current | The Triangle

Materials team explores electron current

A Drexel materials science and engineering professor, along with his team of graduate students and international collaborators, published a paper online Oct. 5 in Physical Review Letters that could pave the way for smaller, more energy efficient computers and other devices.

Jonathan Spanier and graduate student Guannan Chen, the lead author of the published research, were able to use light to excite an electron to the point where it had enough energy to be classified as “hot.” The team also consisted of graduate students Oren Leaffer and Terrence McGuckin, postdoctoral researcher Eric Gallo, and two research scientists in Italy.

The group took advantage of the surface-to-volume ratio in a nanowire, and during the excited state of the electrons, they observed an unusual electronic property. As the electrons shift from the core of the wire to the outer portion, due to their energy and momentum, the researchers manipulated the phase of the electronic current.

The result was a region of negative resistance, the onset of which, for the first time, could be tuned. This discovery has the potential to be a building block for innovations in technology concerning energy and size efficiencies.

“We weren’t looking for this,” Spanier said. “When we work in the laboratory, we always keep an eye open for the unexpected, and I think being nimble and open-minded in the lab can really make for some very pleasant surprises that generate opportunities.”

Although there is still more work to be done with this discovery, Drexel has applied for a provisional patent on the research as a vote of confidence for everyone involved and in the interest of providing more time for the team. Spanier and his fellow researchers now have a year to hone and prepare their findings for practical, marketable applications.

“What people fail to realize is that when you make things smaller, you open markets,” Spanier said. “There are more products that will be created that we can’t even think of today.”

He continued, “Right now there are companies making products and markets based on nanowire technology, and this has the potential of really adding to that.”

The team, working at Drexel, relied on their international counterparts in their research. After being introduced to Paola Prete and Nico Lovergrine, Spanier realized that he and the married Italian scientists had complementary knowledge and expertise.

“It’s not different at all for us to be able to work together,” Spanier said, in regard to the distance.

Besides the added brainpower, students collaborating on the project get a chance to understand how science is conducted in other places.

“There are great challenges, and we feel invigorated by the success that we’ve had. And we want to try to use that momentum to try to move it forward,” Spanier said.

Spanier has been working as an associate professor of materials science and engineering for eight years and currently serves as associate dean for the College of Engineering.

After completing his master’s at Catholic University, receiving his doctorate from Colombia University and completing a postdoctoral fellowship at Harvard, he began his work at Drexel. Spanier’s interest in nanowires was sparked by the fact that they have, as he put, “the benefit of connectivity but the excitement of a finite size in which electrons and other excitations are confined spatially.”

“This causes them to have different properties than when it’s in bulk form,” he continued.

Although it was a long process, there wasn’t one single, defining moment of discovery. Spanier described the different stages as “attempted denial, skepticism, anxiety.”

“It’s very much a ‘living thing,’ and this is certainly not the end of the story,” he said. “There are great challenges, and we feel invigorated by the success that we’ve had. … We want to try to use that momentum to try to move it forward.”