Machine Design

Nanomagnets play by their own rules

Scientists at the National Institute of Standards and Technology (NIST) and Brookhaven National Laboratory report that certain nanocomposite materials seem to ignore the conventions of physics.

The materials, which are used in computer memories and other technologies, undergo a previously unrecognized shift in the rate at which magnetization changes at low temperatures.

The apparent anomaly, described as an "upturn" in magnetization, may be due to the quantummechanical process known as Bose-Einstein condensation. In nanostructured magnets, energy waves called magnons coalesce into a common ground state and, in effect, become one. This collective identity, the researchers say, results in magnetic behavior at odds with long-standing theory.

The finding may lead to a reassessment of test methods used to predict properties of "ferromagnetic" materials and improvements in the performance of microwave devices.

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