Graphene lines up vacancies for a magnetic moment

With the right engineering, graphene could be made to behave like a ferromagnet, according to new research which has uncovered a so-called tunable Kondo Effect in holey sheet of the 2-dimensional carbon lattice.

Physics Professor Michael S. Fuhrer of the UMD Center for Nanophysics and Advanced Materials says he and his team have shown that vacancies in the graphene lattice have a magnetic moment. These magnetic moments disrupt the conductivity of graphene, especially at low temperatures. This is the Kondo effect, and it is normally associated with non magnetic materials that have been doped with magnetic atoms.

"This opens the possibility of 'defect engineering' in graphene - plucking out atoms in the right places to design the magnetic properties you want," said Fuhrer.

According to the release, magnetism in graphene “could lead to new types of nanoscale sensors of magnetic fields…and…have interesting applications in the area of spintronics”.

Fuhrer says finding the effect in a pure carbon structure was surprising. "First, we were studying a system of nothing but carbon, without adding any traditionally magnetic impurities. Second, graphene has a very small electron density, which would be expected to make the Kondo effect appear only at extremely low temperatures," he said.

In this case, however, the effect was observed at temperatures as high as 90 Kelvin, comparable with temperatures you would expect in materials with much higher electron densities.