Magnetic information retained for longer in grown graphene
Researchers from the University of Groningen, the FOM Foundation and the European partnership ConceptGraphene have discovered that the growth of graphene on silicon carbide yields a far longer storage time for magnetic information. They discovered this during their research into the transport of magnetic information in graphene, the carbon crystal lattice one atom thick, with the aim of finding a material with which magnetic information can be processed on a larger scale. This is necessary for use in applications such as quantum computers, for example. The researchers published their results on 20 February 2012 in Nano Letters.
In the discipline of spintronics, researchers make use of the magnetic moment of the electron, the spin, to transport and store information. Electrons become scattered as they move through a material and this leads to a loss of spin information. The loss after a given period of time is called the spin relaxation time and the loss after a given distance the spin relaxation distance. A large relaxation distance is advantageous for spin transport between logic gates. However, it is also important to find materials that retain spin information for a long period of time as these can be used for quantum computing.
Graphene, the thin layer of carbon just one atom thick, has exceptional properties and yielded a Nobel Prize in Physics two years ago. The most investigated form of graphene is made using the technique introduced by Nobel Prize Winners Geim and Novoselov: adhesive tape is used to peel off layers of graphene from a graphite substrate and these are subsequently placed on a silicon oxide substrate. However, the researchers from Groningen used graphene grown on silicon carbide for their experiment. They received this material from fellow researchers in a European project (ConceptGraphene). During spin transport measurements, this graphene exhibited strongly extended spin relaxation times compared to the measurements with 'pealed' graphene. The new substrate is responsible for this striking difference.
The increased spin relaxation times in combination with the scaling up of the graphene signify the next step towards computer operations based on spintronics.
Contact
For further information see nanodevices.nl or contact one of the researchers:
Bart van Wees +31 (0)50 36 34 933
Thomas Maassen +31 (0)50 36 38 973
Jasper van den Berg +31 (0)50 36 34 880
Reference
'Long spin relaxation times in wafer scale epitaxial graphene on SiC(0001)', T. Maassen, J.J. van den Berg, N. IJbema, F. Fromm, T. Seyller, R. Yakimova, B.J. van Wees, Nano Letters (2012), DOI: 10.1021/nl2042497.