New study explains why superconductivity takes place in graphene - Theoretical physicists take important step in development of high temperature superconductors

Graphene, a single sheet of carbon atoms, has many extreme electrical and mechanical properties. Two years ago, researchers showed how two sheets laid on top of each other and twisted at just the right angle can become superconducting, so that the material loses its electrical resistivity. New work explains why this superconductivity happens in a surprisingly high temperature. Researchers at Aalto University and the Ģֱ showed that graphene can be a superconductor at a much higher temperature than expected, due to a subtle quantum mechanics effect of graphene’s electrons. The results were published in Physical Review in Febryary 2020. The findings were highlighted in Physics viewpoint by the American Physical Society, and looks set to spark lively discussion in the physics community.
Artist's view of bilayer graphene. Credit: Antti Paraoanu
Published
28.2.2020

The discovery of the superconducting state in twisted bilayer graphene was selected as the , and it spurred an intense debate among physicist about the origin of superconductivity in graphene.
Although superconductivity was found only at a few degrees above the absolute zero of temperature, uncovering its origin could help understanding high-temperature superconductors and allow us to produce superconductors that operate near room temperature. Such a discovery has been considered one of the “holy grails” of physics, as it would allow operating computers with radically smaller energy consumption than today.

The new work came from a collaboration between professor Päivi Törmä’s group at Aalto University and professor Tero Heikkilä’s group at the Ģֱ. Both have studied the types of unusual superconductivity most likely found in graphene for several years.

“The geometric effect of the wave functions on superconductivity was discovered and studied in my group in several model systems. In this project it was exciting to see how these studies link to real materials”, says the main author of the work, Aleksi Julku from Aalto University.

“Besides showing the relevance of the geometric effect of the wave functions, our theory also predicts a number of observations that the experimentalists can check”, explains Doctoral Student Teemu Peltonen from the Ģֱ.

Link to the article in Physical Review B:

Link to Physics Viewpoint –article:

For further information:
Teemu Peltonen, Ģֱ Teemu.J.Peltonen@student.jyu.fi
Aleksi Julku, Aalto University Aleksi.Julku@aalto.fi
Long Liang, Aalto University, Long.Liang@su.se
Tero Heikkilä, Ģֱ, The Department of Physics and Nanoscience Center, Tero.T.Heikkila@jyu.fi, tel. +358408054804
Päivi Törmä, Aalto University, Paivi.Torma@aalto.fi, tel., +358503826770

Communications officer Tanja Heikkinen, tanja.s.heikkinen@jyu.fi, tel. 358 50 581 8351
The Faculty of Mathematics and Science:
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