Graphene on the way to superconductivity

phys.org | 11/9/2018 | Staff
darkkazune (Posted by) Level 3


Scientists at HZB have found evidence that double layers of graphene have a property that may let them conduct current completely without resistance. They probed the band structure at BESSY II with extremely high resolution ARPES and could identify a flat area at a surprising location. Their research is published in Science Advances.

Carbon atoms can form bonds in multiple ways. Pure carbon can therefore occur in many forms, including diamond, graphite, nanotubes, football molecules or as a honeycomb net with hexagonal meshes, known as graphene. This exotic, strictly two-dimensional material conducts electricity well, but is not a superconductor. But perhaps this can be changed.

April - Group - MIT - US - Form

In April 2018, a group at MIT in the U.S. showed that it is possible to generate a form of superconductivity in a system of two layers of graphene under very specific conditions. To do this, the two hexagonal nets must be twisted against each other at a 1.1 degree angle. Under this condition, a flat band forms in the electronic structure. The preparation of samples from two layers of graphene with such an exactly adjusted twist is complex, and not suitable for mass production. Nevertheless, the study has attracted a lot of attention among experts.

But there is one more, much simpler way of flat band formation. This was shown by a group at the HZB around Prof. Oliver Rader and Dr. Andrei Varykhalov with investigations at BESSY II.

Samples - Prof - Thomas - Seyller - TU

The samples were provided by Prof. Thomas Seyller, TU Chemnitz. There they are produced using a process that is also suitable for the production of larger areas and in large quantities: A silicon carbide crystal is heated until silicon atoms evaporate from the surface, leaving first a single-layer of graphene on the surface, and then a second layer of graphene. The two graphene layers are not twisted against...
(Excerpt) Read more at: phys.org
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