A laser pulse, a special material and an extraordinary property that appears inexplicable are the main elements that emerge from research conducted by an international team of scientists. The team was coordinated by Michele Fabrizio and was made up of Andrea Nava and Erio Tosatti from SISSA, Claudio Gianetti from the Università Cattolica di Brescia and Antonie Georgest from the Collège de France. The key element of the study is a compound of the most symmetrical molecule that exists in nature, namely C60 bucky-ball, a spherical fullerene.
It is well known that this compound, with the chemical formula K3C60 can behave as a superconductor below a critical temperature of 20 degrees Kelvin.
It has recently been discovered the K3C60 is capable of transforming into a high-temperature superconductor when struck by an extremely brief laser pulse. This material takes on superconductive properties, briefly, up to a temperature of -73 degrees Centigrade, almost 100 degrees above the critical equilibrium temperature.
K3C60 is a compound in which purely molecular features coexist alongside metallic properties, a characteristic shared by so-called “strongly correlated” materials. According to the theory developed by researchers in the study, the laser beam creates a high-energy molecular excitation. But in order to do so, it must absorb heat from the low-energy metallic component, which then cools. As it is specifically the metallic component involved in conduction, its cooling may lead to a superconductivity phase despite the external temperature being higher than the critical temperature.
"It is an example of laser cooling, yet with a new operating mechanism which had never been proposed until now. The fact that the laser pulse can transiently change the characteristics of a material is a significant observation. It may offer the prospect of manufacturing electronic devices whose properties change with the use of light as if it were a switch. Indeed, the ultra-rapid control of materials with light sources is of great current interest for the scientific community and for the possible technological ramifications of these applications,” explained the researchers.
A paper in on this study was published in the journal Nature Physics.