(July 10, 2015) Groundbreaking
work at two Department of Energy national laboratories has confirmed
plutonium’s magnetism, which scientists have long theorized but have never been
able to experimentally observe. The advances that enabled the discovery hold
great promise for materials, energy and computing applications.
Plutonium was first produced in 1940 and its unstable
nucleus allows it to undergo fission, making it useful for nuclear fuels as
well as for nuclear weapons. Much less known, however, is that the electronic
cloud surrounding the plutonium nucleus is equally unstable and makes plutonium
the most electronically complex element in the periodic table, with
intriguingly intricate properties for a simple elemental metal.
While conventional theories have successfully explained
plutonium’s complex structural properties, they also predict that plutonium
should order magnetically. This is in stark contrast with experiments, which
had found no evidence for magnetic order in plutonium.
Finally, after seven decades, this scientific mystery on
plutonium’s “missing” magnetism has been resolved. Using neutron scattering,
researchers from the Department of Energy’s Los Alamos and Oak Ridge (ORNL)
national laboratories have made the first direct measurements of a unique
characteristic of plutonium’s fluctuating magnetism. In a recent paper in the
journal Science Advances, Marc Janoschek from Los Alamos, the paper’s lead
scientist, explains that plutonium is not devoid of magnetism, but in fact its
magnetism is just in a constant state of flux, making it nearly impossible to
detect.