Smallest Swiss cross made of 20 single atoms
July 17, 2014
University of Basel physicists with teams from Finland and Japan were able to place 20 single bromine atoms on a fully insulated surface at room temperature to form the smallest “Swiss cross,” taking a step towards next-generation atomic-scale storage devices.
Nature Communications has published their results.
Ever since the 1990s, physicists have been able to directly control surface structures by moving and positioning single atoms to certain atomic sites.
A number of atomic manipulations have previously been demonstrated both on conducting or semiconducting surfaces, mainly under very low temperatures. However, fabrication of artificial structures on an insulator at room temperature is still a long-standing challenge and previous attempts were uncontrollable and did not deliver the desired results.
In this study, an international team of researchers around Shigeki Kawai and Ernst Meyer from the Department of Physics at the University of Basel developed the first successful systematic atomic manipulation on an insulating surface at room temperature.
Using the tip of an atomic force microscope, they placed single bromine atoms on a sodium chloride surface to construct the shape of the Swiss cross. The tiny cross is made of 20 bromine atoms and was created by exchanging chlorine with bromine atoms. It measures only 5.6 square nanometers and represents the largest number of atomic manipulations ever achieved at room temperature.
New storage devices
Together with theoretical calculations the scientists were able to identify the novel manipulation mechanisms to fabricate unique structures at the atomic scale. The study shows how systematic atomic manipulation at room temperature is now possible and represents an important step towards fabrication of a new generation of electromechanical systems, advanced atomic-scale data storage devices and logic circuits, the researchers say.
Abstract of Nature Communications paper
Atomic manipulation enables us to fabricate a unique structure at the atomic scale. So far, many atomic manipulations have been reported on conductive surfaces, mainly at low temperature with scanning tunnelling microscopy, but atomic manipulation on an insulator at room temperature is still a long-standing challenge. Here we present a systematic atomic manipulation on an insulating surface by advanced atomic force microscopy, enabling construction of complex patterns such as a ‘Swiss cross’ of substitutional bromine ions in the sodium chloride surface.