Innovative Laser Techniques Reveal Class of Materials with Potential for Energy Efficiency

An experiment at the cutting edge of materials science and condensed matter physics has shown that the dream of more efficient energy usage can indeed become a reality. This would be another step closer to realizing superconductivity at room temperature.

An international partnership, led by the researchers of Italy’s International School for Advanced Studies (SISSA) in Trieste, Università Cattolica di Brescia and Politecnico di Milano used suitably customized laser pulses to snap the electronic interactions in a compound containing oxygen, copper, and bismuth. In this manner they were able to identify the condition for which the electrons do not repel each other, that is a vital prerequisite for current to flow without hindrance. This research paves way for new perspectives for the progress of superconducting materials with applications in diagnostics, electronics, and transport. The research has been published in Nature Physics.

Using advanced laser methods that make it possible to examine the so-called non-equilibrium system, the researchers discovered a very original way to comprehend the properties of a special class of materials. The SISSA team handled the theoretical phases of the research while the I-LAMP labs of Università Cattolica del Sacro Cuore (Brescia) and Politecnico di Milano organized the experimental phase.

“One of the greatest obstacles to exploit superconductivity in everyday technology is that the most promising superconductors tend to turn into insulators at high temperatures and for low doping concentrations”, the researchers explained. “This is because the electrons tend to repel each other instead of pairing up and moving in the direction of the current flow”.

To examine this phenomenon, the researchers concentrated on a specific superconductor, which has highly intricate chemical and physical properties, being composed of four diverse types of atom including oxygen and copper.

“Using a laser pulse, we drove the material out of its equilibrium state. A second, ultra-short pulse then enabled us to disentangle the components that characterize the interaction between the electrons while the material was returning to equilibrium. Metaphorically, it was like taking a series of snapshots of the different properties of that material at different moments”.

Through this method, the researchers found that “in this material, the repulsion between the electrons, and therefore their insulating properties, disappears even at room temperature. It is a very interesting observation as this is the essential prerequisite for turning a material into a superconductor”. What is the following step in accomplishing this? “We will be able to take this material as a starting point and change its chemical composition, for example”, the researchers explained. Having discovered that the fundamentals for creating a superconductor at room temperature exist, researchers at present have new tools at their disposal for locating the correct recipe: by altering a few ingredients, they probably are not too far away from the perfect formula.

Potential applications? The magnetic field produced by passing a current via a superconductor could be used for a new generation of magnetic levitation trains – much like the one that links Shanghai to its airport - featuring far better efficiency and performances. In diagnostics, it would be possible to produce very large magnetic fields in very small spaces, thus enabling high-accuracy magnetic resonance imaging to be performed on a very small scale. In the field of microelectronics or energy transport, high-temperature superconductors would provide very high efficiency and, simultaneously, substantial energy savings.