'Spinplasmonics' Field Created

By combining two nanotechnology fields -- spintronics and plasmonics -- researchers have found a novel way to control the quantum state of an electron's spin and created a new technology, "spinplasmonics."

A University of Alberta research team lead by Abdulhakem Elezzabi combined the two fields and said that they believe spinplasmonics may be used to create incredibly efficient electron spin-based photonic devices, which in turn may be used to build, for example, computers with extraordinary capacities.

"We've only just begun to scratch the surface of this field, but we believe we have the physics sorted out and one day this technology will be used to develop very fast, very small electronics that have a very low power consumption," said Elezzabi, the Canada Research Chair in Ultrafast Photonics and Nano-Optics and an electrical and computer engineering professor at the U of A.

Elezzabi's work addresses a number of challenges that, to this point, have hindered further advancement in computer electronics, such as in the creation of smaller devices. One such challenge is that as traditional, silicon-based semiconductor devices approach the nanoscale, the laws of quantum physics take control over their performance (specifically the flow of charges, i.e. electrons) and render them inoperable.

Researchers in the field of spintronics have tried to address this problem by building metal-based devices that harness the magnetic quantum properties of the spin of electrons. Although the spintronics field is barely a dozen years old, some devices that incorporate the technology are already on the market.

The field of plasmonics, which is even younger than spintronics, involves the transfer of light electromagnetic energy into a tiny volume, creating intense electric fields -- a phenomenon that has many scientists rethinking the laws of electromagnetics on a nanoscale. The plasmonics field has many wide-ranging applications, from guiding light through metal wires to biosensing to making objects invisible to the eye.

One of the main challenges for plasmonics researchers is finding a way to propagate light over a long distance through solid materials. However, Elezzabi and his colleagues, U of A graduate student Kenneth Chau and Mark Johnson of the US Naval Research Laboratory, have successfully combined plasmonics and spintronics in a way that puts plasmonics in a new light, and puts a new spin on spintronics.

Working with gold and cobalt samples, Elezzabi and his team were able to demonstrate a plasmonically-activated spintronic device that switches light on and off by controlling electron spins. Also, they believe that with a slight alteration of the sample structure, the effect is nonvolatile, meaning that any given result can be maintained indefinitely without the necessity of a power source.

"With the development of this technology I envision a move from semiconductors (silicon chips) to metal-based electronics with light-driven circuits," Elezzabi said.

The work was published recently in the journal Physical Review Letters and the researchers have filed to patent the applications developed.

"To me this is almost a natural evolution of the two fields. I'm actually surprised that no one else looked around and saw what others were doing and combined the two before we did," Elezzabi said. "This opens up a lot of possibilities; this is just the beginning."

For more information, visit: www.ece.ualberta.ca/~elezzabi/