A Two Layers Graphene Superconductor Material

Article by Dr. Olivier Alirol, Physicist, Resonance Science Foundation Research Scientist

Scientists have discovered that a two graphene layers can conduct electrons showing superconductivity if the two hexagonal nets are twisted against each other at a 1.1 degree angle. This finding could lead to room-temperature superconductors, a hypothetical material exhibiting superconductivity at temperatures above 0 °C (273.15 K). Most superconductors work only at temperatures close to absolute zero. Even ‘high-temperature’ superconductors are working in reality at  −140 ºC. A material that displayed the property at room temperature — eliminating the need for expensive cooling — could revolutionize energy transmission, medical scanners and transport.

Increasing the temperature at which superconductivity occurs could have phenomenal technological applications

A current that could flow forever without losing any energy means transmission of power with virtually no losses in the cables. When renewable energy sources start to dominate the grid and high-voltage transmission across continents becomes important to overcome intermittency, lossless cables will result in substantial savings.

 After a first discovery in April 2018, showing superconductivity in a system of two layers of graphene under very specific conditions, physicists now report their conclusions in understanding the mechanism beyond this conperconductivity. Bilayer graphene (BLG) has, along with related two-dimensional (2D) materials, extensively been studied by both transport and photoemission measurements. It is a material with an energy gap that opens as soon as an asymmetry is imposed on the two graphene layers.

The team from Helmholtz-Zentrum in Germany explained the mechanism of the flat band appearance and show that, by influencing sublattice and interlayer asymmetries, one can radically control the band shape and its properties.

"One of the bottlenecks of high-temperature superconductivity has been the fact that we don’t understand, even now, what’s really gluing the electrons into pairs."

Learn more at:

• Phys.org: Graphene on the way to superconductivity
• Scientificamerican.com: Surprise Graphene Discovery Could Unlock Secrets of Superconductivity
• Sciencemag.org: Extremely flat band in bilayer graphene

   
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