Researchers at the University of Vienna, Austria, have pioneered a technique that uses electron beams to manipulate single atoms, making it possible to control the movement of individual silicon impurity atoms within the lattice of graphene.

Building on work published over the past few years, a research team at the university led by Toma Susi has now used the advanced electron microscope Nion UltraSTEM100 to manipulate single atoms in graphene with atomic precision.

Even with manual operation, the achieved movement rate is already comparable to the state-of-the-art technology in any atomically precise technique. Susi said: “The control we are able to achieve by essentially directing the electron beam by hand is already remarkable, but we have further taken the first steps towards automation by detecting the jumps in real time.”

The recent results also improve theoretical models of the process by including simulations by collaborators in Belgium and Norway.

What did the researchers achieve?

In total, the researchers recorded almost 300 controlled jumps. Additional to extended paths or moving around a single hexagon made of carbon atoms in graphene, a silicon impurity could be moved back and forth between two neighbouring lattice sites separated by one tenth-billionth of a meter, like flipping an atomic-sized switch.

This could, in principle, be used to store information at a record-high density. Susi concluded: “Your computer or cell phone will not have atomic memories anytime soon, but graphene impurity atoms do seem to have potential as bits near the limits of what is physically possible.”

Using nanotechnology to manipulate single atoms

As a significant achievement in nanotechnology, the scanning tunnelling microscope has been able to move atoms over surfaces since the 1980s. Until recently, however, it has been the only technology capable of moving single atoms in a controlled way.

Now, the scanning transmission electron microscope (STEM) can reliably focus an electron beam with sub-atomic precision, allowing scientists to directly see each atom in two-dimensional materials like graphene and to target single atoms with the beam. Each electron has a tiny chance of scattering back from a nucleus, moving it in the opposite direction.

The research conducted at the University of Vienna was funded primarily by the European Research Council (ERC) and the Austrian Science Fund (FWF).

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