In 2010 the Nobel Prize in physics was awarded for the discovery of the exceptional material graphene, which consists of a single layer of carbon atoms arranged in a honeycomb lattice. But graphene research did not stop there. New interesting properties of this material are still being found. An international team of researchers has now explained the peculiar behaviour of electrons moving through narrow constrictions in a graphene layer. The results have been published in the journal Nature Communications.
"When electrical current flows through graphene, we should not imagine the electrons as little balls rolling through the material", says Florian Libisch from TU Wien (Vienna), who led the theoretical part of the research project. The electrons swash through the graphene as a long wave front, the wavelength can be a hundred times larger than the space between two adjacent carbon atoms. "The electron is not confined to one particular carbon atom, in some sense it is located everywhere at the same time", says Libisch.
The team studied the behaviour of electrons squeezing through a narrow constriction in a graphene sheet. "The wider the constriction, the larger the electron flux - but as it turns out, the relationship between the width of the constriction, the energy of the electrons and the electric current is quite complex", says Florian Libisch. "When we make the constriction wider, the electric current does not increase gradually, it jumps at certain points. This is a clear indication of quantum effects."
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