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Physicist aims to create magnetized electron source

Physicist aims to create magnetized electron source
Building a better light bulb, harnessing nuclear fusion or even researching the beginning of life on Earth requires magnetized electrons. To date, creating these special “spin-polarized electrons” is difficult and time-consuming.

UNL physicist Tim Gay is developing a turnkey source of spin-polarized electrons with a $610,000 grant from the National Science Foundation funded by the American Recovery and Reinvestment Act (ARRA).

Manipulating the negative charge of electrons, which are atomic particles, plays an important role in energy use and production.

Now scientists are learning to harness another property of electrons – their spin. Electrons spin on an axis, generating magnetic energy. Normally, they spin randomly, canceling out each other’s magnetism, which is why most objects are not magnetic.

But get all of those electrons spinning in the same direction so that they are “spin-polarized,” and as a group they become magnetized, opening up many research and high-tech applications.

Exploiting electron spin through spin-polarized electrons, called “spintronics,” has the potential to create smaller, faster electronic components that require less energy. Other research based on spin-polarized electrons will create, for example, more energy-efficient light bulbs, more effective medical imagers and faster computers.

“The production of a spin-polarized electron source has the potential to be a beneficial high-tech tool in labs that are interested in creating better computer memories, for example,” said Gay. “That would be a big help for the computer industry.”

To create a convenient source, Gay is looking at optical pumping. This involves aiming a laser of spin-polarized photons at rubidium atoms in a vapor to force the rubidium’s electrons to spin in the same direction, turning the vapor into a large magnet. Next, a beam of randomly spinning electrons is shot through the vapor. The electrons exchange places so that the gas is no longer magnetized, but the electrons coming out the other side are spinning in one direction and are magnetized.

The ARRA grant allowed Gay to hire three undergraduate and three graduate students and to purchase a U.S.-made laser.

Ashley Ernesti of Lincoln, Neb., a senior physics major hired for the project, said she’s getting valuable hands-on training as she applies for graduate school.

“Working on this project has been a really great learning experience,” Ernesti said. “I haven’t had much lab experience, and I’ve been wondering if I want to go into theoretical or experimental research. That isn’t something you can learn in a classroom.”

“We are enhancing the technological face of the U.S. economy by turning out students with tech backgrounds,” Gay said. “This is really an ideal training ground for tomorrow’s workers in high-tech facilities.”

A turnkey energy source may also help his team answer intriguing questions about life, such as why all DNA molecules spiral in the same direction. The answer may have to do with cosmic rays – a natural source of spin-polarized electrons.