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Researchers have made advances in understanding a material that could be key to the next generation of computers, more powerful than today’s silicon-based machines.

“…if you think about those two phases as being analogous to a zero and a one, you can come up with some interesting new ways of information processing.”

The existing paradigm of silicon-based computing has given us a range of amazing technologies, but engineers are starting to discover silicon’s limits. As a result, for computer science to keep advancing it is important to explore alternative materials that could enable different ways to do computation, according to Patrick J. Shamberger, assistant professor in the department of materials science and engineering at Texas A&M University. Vanadium dioxide is one example.

“It’s a very interesting, chameleon-like material that can easily switch between two different phases, from being an insulator to being a conductor, as you heat and cool it or apply a voltage,” says Sarbajit Banerjee, professor with joint appointments in the chemistry and materials science and engineering departments. “And if you think about those two phases as being analogous to a zero and a one, you can come up with some interesting new ways of information processing.”

“Before vanadium dioxide can be used in computing, we need to better control its transition from insulator to conductor and back again,” Shamberger says. In a new paper in the journal of Chemistry of Materials, the team describes doing just that by adding tungsten to the material.

Among other things, the researchers showed that tungsten allows the transition to occur over two very different pathways. The result is that the transition from insulator to conductor happens easily and quickly, while the transition from conductor back to insulator is more difficult.

“Think of it as driving from point A to point B and back again. Going there you take a superhighway, but coming back you’re on back roads,” Banerjee says.

Essentially the addition of tungsten allows the vanadium oxide to switch quickly in one direction and much more slowly in the other, phenomena that could be exploited in future computers.

“It provides an additional ‘knob’ to tune how you go back and forth between the two states,” says first paper author Erick J. Braham, a graduate student at Texas A&M.

The team has also found that the addition of tungsten allows them to better control, or tune, the different temperatures where the transitions occur.

Banerjee notes the interdisciplinary nature of the work, which involved four groups with expertise ranging from computational materials science to electron microscopy, has been key.

“We’ve really looked at this puzzle from different ends to try to make sense of exactly what’s going on,” he says. “It’s been very exciting.”

Additional authors of the paper are from Texas A&M and the University of Illinois at Chicago. The National Science Foundation and the Air Force Office of Scientific Research supported their work.

Source: Texas A&M University