Laser beams for superconductivity

It is well known that this compound, with the chemical formula K₃C₆₀, can behave as a superconductor -- that is, conduct without dissipating energy -- below a critical temperature of 20 degrees Kelvin, or around -253 degrees Celsius.

It has recently been discovered that K₃C₆₀ is capable of transforming into a high-temperature superconductor when struck by an extremely brief laser pulse. This material takes on superconductive properties -- albeit extremely briefly -- up to a temperature of -73 degrees Centigrade, almost 100 degrees above the critical equilibrium temperature. The research just published by the scientists explains the reason for this mysterious behaviour.

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 the researchers in this study, the laser beam creates a high-energy molecular excitation, yet in order to do so it must absorb heat from the low-energy metallic component, which thus cools. As it is specifically the metallic component involved in conduction, its cooling may lead to a superconductivity phase despite the external temperature is higher than the critical temperature.

As the researchers explain: "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."