Green paint may be rosy dawn for new technology

Researchers at the University of Washington have announced the discovery of intriguing new properties in a paint pigment first formulated in 1780.

The scientists revealed their findings in the paper Direct Kinetic Correlation of Carriers and Ferromagnetism in Co2+:ZnO, published in the 21 July edition of Physical Review Letters. 

The pigment, cobalt green, a semi-transparent compound made by heating a mixture of zinc oxide and cobalt, has been found to have magnetic qualities that may make it suitable for a whole new family of hitherto impracticable "spintronic" devices based on the inherent magnetic nature of electrons, the researchers claim. 

"This work shows there is a real effect here, and there is promise for these materials," said Daniel Gamelin, assistant professor of chemistry at the University of Washington and co-author of a paper describing the work, in a statement. "The next step is to try to get these materials to interface with silicon semiconductors."

Spintronics is a form of logic and memory that relies on changing the spin of electrons — which defines their magnetic effects — instead of purely their location. In theory, this requires a lot less energy and can be a lot more stable than with conventional devices, leading to much lower power systems with much better data retention capabilities than at present. However, the physics which might lead to practical spintronic devices currently only works at an impractical minus 200 Celsius.

"The big challenge is to develop materials that can perform these kinds of functions not just at cryogenic temperatures but at practical temperatures," said Gamelin. "The breakthrough with the materials we tested is that they exhibit their magnetic properties at room temperature."

The researchers' experiments on cobalt green showed that the cobalt ions could be aligned — having their electrons' spin manipulated — by the influence of extra electrons in zinc. Once those electrons were removed, the alignment persisted without cooling, making the compound one of the strongest candidates yet found for practical development.

Because development of these materials is in the early stages, it is not yet clear what their final properties will be, and their final properties will determine how they can be used, Gamelin said.