Graphene, the world’s thinnest and strongest material, is a sheet of carbon atoms arranged in a chicken-wire structure. In its pristine state, it exhibits no signs of the conventional magnetism usually associated with such materials as iron or nickel.
Dr Irina Grigorieva, the project’s lead researcher and a senior lecturer at Manchester University, told The Engineer: ’Our study demonstrates that one can use relatively simple modifications to make graphene magnetic, adding magnetism to the already long list of this material’s amazing properties.
‘This is remarkable because magnetism is usually associated with the so-called transition metals, such as iron or nickel, and has not been expected to occur in a material made up from just carbon atoms,’ she explained.
The Manchester researchers, including Nobel prize winner Prof Sir Andre Geim, took non-magnetic graphene and then either ‘peppered’ it with other non-magnetic atoms such as fluorine or removed some carbon atoms from the chicken-wire structure by knocking them out with energetic ions (protons). The empty spaces, called vacancies, and added atoms all turned out to be magnetic.
‘We attached more and more atoms of fluorine until every carbon atom in graphene was bonded to a fluorine,’ said Grigorieva.
She added: ‘Of all the attached fluorine atoms, only those that were sufficiently far away from each other added to graphene’s magnetism, while neighbouring adatoms effectively cancelled out each other’s magnetic moments.
‘In a similar way, the magnetic vacancies could not be placed too close together for the obvious reason that graphene with too many “holes” in it is no longer graphene.’
Geim said in a statement that the observed magnetism is tiny and even the most magnetised graphene samples would not stick to a fridge.
He explained that the most likely use of magnetised graphene lies in spintronics. Spintronic devices are most notably found in computer hard disks and they function as a result of coupling magnetism and electric current.