Subtle electronic effect in magnetite discovered: Long-standing puzzle in study of magnetism finally solved

ScienceDaily (Dec. 21, 2011) — A fundamental problem that has long puzzled scientists has been solved after more than 70 years. An international team of researchers has discovered a subtle electronic effect in magnetite, the most magnetic of all naturally occurring minerals. The effect causes a dramatic change to how this material conducts electricity at very low temperatures.

The discovery gives new insight into the mineral in which magnetism was discovered, and it may enable magnetite and similar materials to be exploited in new ways.

Ancient knowledge

Magnetite's properties have been known for more than 2000 years and gave rise to the original concepts of magnets and magnetism. The mineral has formed the basis for decades of research into magnetic recording and information storage materials.

The research was led by the University in collaboration with the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, where the experiments were conducted. Their results were published in Nature.

Unexplained behaviour

In 1939, Dutch scientist Evert Verwey discovered that the electrical conductivity of magnetite decreases abruptly and dramatically at low temperatures. At about 125 Kelvin, or minus 150 degrees Celsius, the metallic mineral turns into an insulator.

Despite many efforts, until now the reason for this transition has been debated and remained controversial.

X-ray experiment

The team of scientists fired an intense X-ray beam at a tiny crystal of magnetite at very low temperatures. Their results enabled them to understand a subtle rearrangement of the mineral's chemical structure. Electrons are trapped within groups of three iron atoms, where they can no longer transport an electrical current.

"We have solved a fundamental problem in understanding the original magnetic material, upon which everything we know about magnetism is built," said Professor Paul Attfield, Centre for Science at Extreme Conditions. "This vital insight into how magnetite is constructed and how it behaves will help in the development of future electronic and magnetic technologies."

The research was funded by the Science and Technology Facilities Council, the Engineering and Physical Sciences Research Council, and the Leverhulme Trust.

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Journal References:

Mark S. Senn, Jon P. Wright, J. Paul Attfield. Charge order and three-site distortions in the Verwey structure of magnetite. Nature, 2011; DOI: 10.1038/nature10704J. Paul Attfield. Condensed-matter physics: A fresh twist on shrinking materials. Nature, 2011; 480 (7378): 465 DOI: 10.1038/480465a

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Recent trends show recession's effect on US advanced technology exports

ScienceDaily (Sep. 6, 2011) — U.S. exports of advanced technology products (ATP) fared better than other non-advanced technology exports during the recent U.S. recession, says a new report from the National Science Foundation (NSF).

NSF's National Center for Science and Engineering Statistics reports that ATP exports fell from $270 billion in 2008 to $245 billion in 2009. But this 9 percent drop was less than half the decline of non ATP exports.

ATP exports embody new or leading edge breakthroughs in science and technology including drugs developed from gene therapy, nuclear resonance imaging, micro integrated circuits, robotics, advanced materials, and civilian and military satellites.

The finding results from U.S. Census Bureau data taken from ATP trade in the 10 ATP technology areas defined by the agency with a focus on four technology areas: aerospace, electronics, information and communications technology and life science. Together these four areas account for 85 percent of U.S. ATP exports in 2010.

NSF's report, titled "U.S. Exports of Advanced Technology Products Declined Less Than Other U.S. Exports in 2009," also says U.S. ATP exports recovered in 2010 but lagged behind the growth of non-ATP exports. In 2010, U.S. ATP exports improved by 11 percent as compared to 2009, but other types of U.S. exports expanded at 23 percent, twice the rate of ATP exports.

The InfoBrief also describes U.S. ATP trade with selected major economies and regions. It says the 2009 decline of US ATP exports was steeper for Asia as compared to those destined for the European Union and the North American Free Trade Agreement zone.

Exports to Asia fell from $94 billion in 2008 to $79 billion in 2009; at 15 percent, it was the largest decline among the three regions. According to NSF's report, the decline was driven by a drop in electronics exports to Asia, the most important export market for U.S. advanced technology products, and a drop in information and communications technology exports.

During the period of 2008-2009, U.S. ATP exports to Japan, South Korea and Taiwan declined steeply (between 19 and 29 percent), but exports to China saw little change. In 2010, however, US exports to Asia grew faster than US exports to the other two regions.

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