When "frustrated" by their arrangement, magnetic atoms surrender their individuality, stop competing with their neighbors and then practice a group version of spin control—acting collectively to achieve local magnetic order—according to scientists from the Commerce Departments National Institute of Standards and Technology, Johns Hopkins University and Rutgers University writing in the Aug. 22, 2002, issue of the journal Nature.
Chill! Atoms in zincochromite, a "geometrically frustrated magnet," resolve their frustration through group spin control. Neighboring tetraheda (solids with four triangular faces) contribute a side each to create hexagonal (six-sided) spin clusters. A hexagon bunches the spins of magnetic atoms-one at each corner-into a single "spin director" (arrows). The composite behavior achieves local magnetic order.
The unexpected composite behavior detected in experiments done at the NIST Center for Neutron Research (NCNR) accounts for the range of surprising—and, heretofore, unexplainable—properties of so-called geometrically frustrated magnets, the subject of intensifying research efforts that may lead to new types of matter. The finding also may shed light on natural clustering processes including the assembly of quarks and other minuscule components into atoms, the folding of proteins and the clumping of stars in galaxies, the scientists say.
These and other important phenomena—including high-temperature superconductivity—suggest that there are "higher-order organizing principles that are intrinsic to nature," explains lead author Seung-Hun Lee, NCNR staff physicist.
Mark Bello | EurekAlert!
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