11th May 2013
New magnetic graphene may revolutionise electronics
Researchers in Spain have managed to give graphene magnetic properties. This breakthrough, published in the journal Nature Physics, opens the door to the development of graphene-based spintronic devices; that is, devices based on the spin or rotation of the electron, which could transform the electronics industry.
TCNQ molecules on graphene layer, where they acquire a magnetic order. Credit: IMDEA-Nanoscience
Scientists were already aware that graphene, an incredible material formed of a mesh of hexagonal carbon atoms, has extraordinary conductivity, mechanical and optical properties. Now it is possible to give it yet one more property: magnetism, implying a breakthrough in electronics.
This is revealed in a study that the Madrid Institute for Advanced Studies in Nanoscience (IMDEA-Nanociencia) and Autonoma Autonomous (UAM) and Complutense (UCM) universities of Madrid have just published in Nature Physics. Researchers managed to create a hybrid surface from this material that behaves as a magnet.
Prof. Rodolfo Miranda, Director of IMDEA-Nanociencia: "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."
Spintronics is based on the charge of the electron, as in traditional electronics, but also on its "spin", which determines its magnetic moment. Material is magnetic when most of its electrons have the same spin. As the spin can have two values, its use adds two more states to traditional electronics. This positioning can be translated into a binary signal (1 or 0). Thus, both data processing speed and quantity of data to be stored on electronic devices can be increased, with applications in fields such as telecommunications, computing, energy and biomedicine.
A TCNQ molecule on the graphene mesh which in turn has been
grown on a ruthenium crystal. Credit: IMDEA-Nanoscience
In order to develop a graphene-based spintronic device, the challenge was to 'magnetise' the material, and researchers from Madrid found how through the quantum and nanoscience world. The technique involved growing an ultra-precise graphene film over a ruthenium single crystal, inside an ultra-high vacuum chamber where organic molecules of tetracyano-p-quinodimethane (TCNQ) are evaporated on the graphene surface. TCNQ is a molecule that acts as a semiconductor at very low temperatures in certain compounds.
On observing results through a scanning tunnelling microscope (STM), scientists were surprised: organic molecules had organised themselves and were regularly distributed all over the surface, interacting electronically with the graphene-ruthenium substrate.
"We have proved in experiments how the structure of the TCNQ molecules over graphene acquires long-range magnetic order, with electrons positioned in different bands according to their spin," clarifies Prof. Amadeo Vázquez de Parga.
Meanwhile, his colleague Prof. Fernando Martin has conducted modelling studies that have shown that, although graphene does not interact directly with the TCNQ, it does permit a highly efficient charge transfer between the substrate and the TCNQ molecules and allows the molecules to develop long-range magnetic order.
The result is a new graphene-based magnetised layer, which paves the way towards the creation of devices based on what was already considered as the material of the future, but which now may also have magnetic properties.
Comments »
