Graphene Becomes Magnetic for First Time

Researchers from both the University of Madrid Complutense and Universidad Autonoma working together at the IMDEA-Nanociencia Institute in Spain have for the first time given graphene magnetic properties,opening up the potential that the material can find new applications in future spintronic devices.

Unlike electronics in which an electron’s charge-carrying capabilities are exploited to create circuits, spintronics involves the quantum mechanical property of electrons to spin, which creates a magnetic moment that makes the electrons behave briefly like magnets. When in the presence of a magnetic field the spin of the electrons moves either into a parallel or antiparallel position in relation to the field. This positioning can be translated into a binary signal (1 or 0).

The trials and tribulations trying to make graphene applicable to electronics despite its lack of an inherent band gap have been well documented. However, what many have overlooked in the quest to bring graphene to electronics is that it doesn’t really lend itself very well to spintronics either.

Since 2007, researchers have looked at graphene as the material for channels in spintronic devices. At this function, it appears to excel. In fact, just this year record distances were achieved for carry information using the spin of electrons.

Unfortunately, when two-dimensional graphene is laid out flat, the motion of electrons moving through the material doesn’t influence the spin of other electrons that they pass. Instead the direction and the spin of electrons remain random rather than patterned.

More than two years ago, researchers at the University of Copenhagen discovered that that all changed if you curved the graphene into a cylinder. In that shape, the movement of electrons did influence the spin of other electrons, opening the door to their potential in spintronics.

In order for a material to be have magnetic properties a majority of the electrons in the material must be spinning in the same direction. Despite the work of the Copenhagen researchers and many others, it has remained a challenge to get graphenes’ electrons to spin in the same direction instead of just randomly. But the Spanish researchers believe they have accomplished it.

“In spite of the huge efforts to date of scientists all over the world, it has not been possible to add the magnetic properties required to develop graphene-based spintronics. However these results pave the way to this possibility," says Prof. Rodolfo Miranda, Director of IMDEA-Nanociencia, in a press release.

The research, which was published in the journal Nature Physics ("Long-range magnetic order in a purely organic 2D layer adsorbed on epitaxial graphene"), first grew ultra pure graphene film over a crystal inside of a vacuum. While still in the vacumm, the researchers evaporated molecules of a semiconductor on the graphene’s surface. When they observed the material with a scanning tunneling microscope, they were surprised to discover that the semiconductor molecules were organized and regularly distributed across the surface of the graphene and its crystal substrate.

Since spintronics hasn't really progressed beyond its application into devices beyond hard-disk drives, the ability to give graphene magnetic properties likely won't bring spintronic devices into other applications any sooner. But these kinds of breakthroughs do have a way of opening up unexpected possibilities.

Photos:  IMDEA-Nanoscience

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Nanoclast

IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.

 
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Dexter Johnson
Madrid, Spain
 
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Associate Editor, IEEE Spectrum
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