Researchers in Switzerland report they've created the country's iconic symbol, the Swiss Cross, at the smallest scale ever, manipulating just 20 individual atoms to create it.
Scientists at the University of Basel say the achievement represents an important step toward the production of devices for data storage or as computer logic gates at an atomic scale.
"Essentially, you can think about it as an ultra-dense storage media, where information can be stored with a few atoms," head researcher Ernst Meyer says.
What marks the accomplishment as significant is that it represents the first time such a manipulation of individual atoms has been done at room temperature; previous attempts to place atom-scale structures on a conducting or semi-conducting surface have required extremely low temperatures.
Until now, room-temperature efforts at creating atom-based nanostructures have been difficult to control and yielded poor results, researchers said.
The Basel team used an atomic force microscope to place 20 atoms of bromine on a surface of sodium chloride to create the form of a Swiss Cross in what is being reported in the journal Nature Communications as the largest group of atoms every manipulated at something close to room temperature.
The researchers manipulated the atoms, causing the bromine atoms to exchange placed with the chlorine atoms, to create the cross only 5.6 nanometers across. A nanometer is a billionth of a meter.
The exchange of atoms was necessary to create a stable structure, the researchers reported; if the bromine atoms simply sat on top of the underlying lattice, the structure would not be secure.
Storage of computer memory at a small scale -- nanoscale memory -- has been a goal of researchers for some time. Scientists at IBM demonstrated that just 12 atoms can be used to store one magnetic bit of information.
The technique could also yield logic circuits at a small scale never before possible, the researchers suggested.
"Alternatively, one may think to create logic circuits as in a processor," Meyer says. "NaCl (sodium chloride) is an insulator. If we can write conducting lines, one may build a network."
Such tiny electrical circuits could be connected to mechanical movement in a number of devices, he says.
"For example, to create high accuracy frequency standards, similar to quartz in a watch or the time base in a computer."
