New study explains why superconductivity takes place in graphene

Theoretical physicists take important step in development of high temperature superconductors
Kuva: Taiteilijan näkemys kaksikerrosgrafeenista. Antti Paraoanu.
Artist's view of bilayer graphene. Antti Paraoanu.

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 University of Jyväskylä 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 . The findings were highlighted in Physics viewpoint by the American Physical Society, and looks set to spark lively discussion in the physics community.

The discovery of the superconducting state in twisted bilayer graphene was selected as the Physics breakthrough of the year 2018 by the Physics World magazine, 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 Päivi Törmä’s group at Aalto University and Tero Heikkilä’s group at the University of Jyväskylä. 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 Teemu Peltonen from the University of Jyväskylä.

Read more at:

A. Julku, T. Peltonen, L. Liang, T.T. Heikkilä, and P. Törmä, Phys. Rev. B 101, 060505 (2020)

Physics viewpoint highlighting the article


Further information:
Aleksi Julku, Aalto University [email protected]
Teemu Peltonen, University of Jyväskylä [email protected]
Long Liang, Aalto University, [email protected]
Tero Heikkilä, University of Jyväskylä, [email protected], tel. +358408054804
Päivi Törmä, Aalto University, [email protected], tel., +358503826770

  • Published:
  • Updated:
URL copied!

Read more news

Lauri Parkkonen and the family cat, Roosa. Photo: Lauri Parkkonen, Aalto, University.
Press releases Published:

New imaging technique to find out what happens in the brains of cats and dogs

A brain imaging device based on quantum optical sensors could also be used to study the brains of human babies
Kuvaa laitteittosta Aalto-yliopsiton Kylmälaboratoriossa.
Press releases Published:

Perpetual motion is possible – Scientists at Aalto University’s Low Temperature Lab observed the interaction of two time-crystals that bend the laws of physics

Time-crystals are a phase of matter in which the particles more in a perpetually repeating cycle with no external input of energy. Researchers were able to create two time-crystals at Aalto University’s Low Temperature Lab and observe their interaction. In the future, time-crystals might have applications in devices such as quantum computer memory components.
Valkoinen laboratoriotakki sekä analyysityökalu, jolla voidaan mitata veripisarasta särkylääkkeen pitoisuus.
Press releases Published:

Portable and quick analytics tool can revolutionise the pain killer diagnostics market

Fepod Oy Ltd, an Aalto University based start-up, has developed an analysis tool that allows healthcare professionals to measure the concentration of paracetamol, opioids and other painkillers real concentration in a single drop of blood.
Yhdistelmäkuva, jossa näkyy revontulia, Maa, mittauksia.
Press releases Published:

Suomi 100 did what could previously be done only by much larger satellites: photographing and studying the aurora borealis

Studying the aurora borealis area helps in the development of safe telecommunications, for example.