A team of researchers from the Department of Energy's Los Alamos and Oak Ridge national laboratories was successful in solving a long-held mystery by confirming plutonium’s magnetism for the first time.

The study authors in an explanation said on Friday that plutonium, first produced in 1940, has an unstable nucleus that allows it to undergo fission. Its unstable nucleus makes it usable in nuclear fuels and weapons.

Researchers said so far very less was known about the cloud of electrons that surrounded its nucleus. This cloud made it electronically more complex element in the periodic table, said authors.

Scientists since long have thought that plutonium had magnetism, but they were never been able to observe it experimentally.

Now researchers using a process known as neutron scattering were able to directly measure one unique characteristic of the element’s fluctuating magnetism for the first time. Results of the study showed that plutonium’s magnetism is in a constant state of flux.

Lead investigator Marc Janoschek said plutonium exists in a state known as a quantum mechanical superposition, which involves two extremes in its electronic configuration.

In one state, its electrons are completely localized around the plutonium ion, and in another, those electrons delocalize and are no longer associated with the ion.

Janoschek and his colleagues used the ARCS instrument at ORNL's Spallation Neutron Source to make neutron measurements, through which they were able to determine that these fluctuations have different numbers of electrons in plutonium’s outer valence shell.

Former Los Alamos laboratory director and plutonium science expert Siegfried Hecker said, “The study provides the best explanation to date as to why plutonium is so sensitive to all external perturbations – something that I have struggled to understand for 50 years now”.