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  • AAAS Awards 'Spin Hall Effect' Team
Feb 2006
ST. LOUIS, Feb. 22, 2006 -- An elusive discovery about the spin effects in semiconducting materials earned a group of researchers the 2004-2005 Newcomb Cleveland Prize, the oldest award conferred by the American Association for the Advancement of Science. The team reported observing the spin Hall effect, the first time it has been seen in an experiment.
The researchers are Yuichiro K. Kato, Roberto C. Myers, Arthur C. Gossard and David Awschalom. They published "Observation of the Spin Hall Effect in Semiconductors" in Science in Dec. 2004. (At the time, the authors' affiliation was the Center for Spintronics and Quantum Computation, University of California [UC], Santa Barbara. Today, Kato is a postdoctoral scholar in the chemistry department at Stanford University.)
Their paper shows the spin effects in semiconducting materials induced by electric fields along the length of the material. The authors were able to show that oppositely directed effects could be induced at the edges, using an elegant optical technique. They then examined possible sources of the effect, showing that it is not the result of intrinsic coupling, but rather a form of scattering that did not depend on the nature of the semiconducting material used.
"The extraordinary care of the experiments and the clarity with which the mechanism of the effect was deduced has led to extraordinary attention from the condensed-matter and materials science communities," said Science Editor-in-Chief Donald Kennedy. "This is an outstanding contribution to the field of physics."
In 1879, Edward Hall placed a thin layer of gold in a strong magnetic field, connected a battery to the opposite sides of this film, and measured the current flowing through it. He discovered that a small voltage appeared across this film that was proportional to the strength of magnetic field multiplied by the current. In 1971, two Russian physicists predicted that a similar effect could be expected in spin physics, but the spin Hall effect defied experimental detection for 33 years.
The Hall effect did not find practical application until the second half of the 20th century, when it was used to mass-produce semiconductor chips; today, it is widely used in sensors and electronics. The research team at UC Santa Barbara first discovered the signatures of the spin Hall effect in semiconductor chips made from gallium arsenide, which are similar to those used in cell phones, and also studied the effect in samples made from indium gallium arsenide. Although the practical applications of the team's discovery are not yet known, they may find use in sensing technologies, quantum computing and quantum communication.
The Cleveland award, presented annually to the author(s) of the best research article or report published in Science, includes a $25,000 cash prize and a bronze medal. It was presented at the 2006 AAAS annual meeting, held last week in St. Louis, Mo. Affymetrix, a Santa Clara., Calif., company that is applying the principles of semiconductor technology to the life sciences, added its support to the Cleveland prize in 2003. The company's founder, chair and CEO Stephen P.A. Fodor and his colleagues, were awarded the prize in 1990 for their landmark publication that introduced microarray technology to the scientific community.
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