Rare type of superconductivity observed in magic-angle twisted trilayer graphene

Shane McGlaun - Jul 22, 2021, 5:01am CDT
Rare type of superconductivity observed in magic-angle twisted trilayer graphene

Physicists at MIT have conducted a study on a material called magic-angle twisted trilayer graphene. The material has exhibited signs of a rare type of super connectivity. Physicists at MIT discovered the material exhibits superconductivity at surprisingly high magnetic fields of up to 10 Tesla.

10 Tesla is a magnetic field strength three times higher than what the material is predicted to endure if it was a conventional superconductor. Results of the experiments imply the magic-angle trilayer graphene is a rare type of superconductor known as a “spin-triplet.” Materials of that type are impervious to high magnetic fields.

The material could vastly improve technologies, including magnetic resonance imaging which relies on superconducting wires under a magnetic field to resonate with and image biological tissue. Currently, MRI machines are limited to magnetic fields of 1 to 3 Tesla. If a new generation of MRI machines could be built with spin-triplet superconductors that operate under high magnetic fields, they could produce sharper and deeper images of the human body.

Spin-triplet superconductors in trilayer graphene could also be leveraged to design stronger superconductors for practical quantum computing. MIT professor of physics Pablo Jarillo-Herrero says the value of the experiment is what it teaches about fundamental superconductivity and how materials behave. Now the team can try design principles for other materials that would be easier to manufacture and possibly provide better superconductivity.

Superconducting materials have a super-efficient ability to conduct electricity without losing energy, and when exposed to electric current, electrons in the superconductor clump in something known as “Cooper pairs.” Those pairs can travel through the material without resistance. In most superconductors, the pairs have opposite spins, with one electron spinning up and the other spinning down, a configuration known as a “spin-singlet,” and can be pulled apart in high magnetic fields.

Materials that superconduct through pairs of electrons with the same spin are known as spin-triplet. Materials of that type, when exposed to high magnetic fields, exhibit both electrons in a Cooper pair shifting the same direction, so they aren’t pulled apart as they are in a spin-singlet.


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