WSU Physics Dept. make accidental discovery that could help advance technology

PULLMAN, WA - A scientist at Washington State University recently made an accidental discovery that could change the way physicists look at electrical conductivity.

We're at Washington State University to find out how researchers can increase the electrical conductivity of a certain crystal, simply by exposing it to light.

"It is exciting, it's very fascinating the fact that we were able to observe this at ordinary room temperature," said WSU Physics Post-Doctoral Research Associate Marianne Tarun.

Marianne Tarun is a Post-Doctoral Research Associate in WSU's Physics Department. She spends a lot of her time researching a crystal called strontium titanate.

"I was measuring the electrical conductivity of my sample, and I observed that it has very low conductivity," said Tarun. "It is essentially insulating."

"But we found that if it was left out in the room, its conductivity would increase over a period of a few days," said WSU Professor of Physics Matthew McCluskey.

"And I was surprised," said Tarun. "And so we initially thought that this could be due to some surface contamination on the sample."

"So Marianne looked at this, really over a period of a year, a year and a half," said McCluskey. "And finally we found that in fact, it was the room lights that were causing this effect."

It turns out that light increases the conductivity of the crystal by hundreds of times. And when the lights go off, the crystal keeps its ability to transmit a current.

"For the first time, we see this effect at room temperature, that we can really get this persistent conductivity at room temperature, which has never been seen before," said McCluskey.

"This could lead to practical devices," said Tarun.

The strontium titanate could potentially be used in computer memory to increase its information capacity.

"That kind of thing is probably ten or fifteen years off, it's very speculative," said McCluskey. "But that's the kind of technological application that could result from this very unusual behavior."

There's still a lot of research to be done on this material to find out how it uses light to become a conductor, and it's all happening right here on campus.

The research was funded by The National Science Foundation and it'll appear in this month's edition of a scientific journal called 'Physical Review Letters.'