DC Josephson effect in Magic-Angle Twisted Bilayer Graphene

Novel electronic devices will be based on fundamentally different electronic phases in one and the same material.
Connecting normal metals, superconductors, magnets and various insulators in a single crystal, holds great promise for applications in superconducting electronics and quantum information technology.
Recently, all these states of matter have been discovered in magic angle twisted bilayer graphene, of which the gate tunability of the superconducting state caught most attention.
Here we use magic-angle twisted bilayer graphene to electrostatically define a Josephson junction, and investigate the observed DC Josephson effect.
We show that superconductivity is induced in the different electronic bands, both flat and dispersive, and describe the Josephson junction behaviour in terms of these bands, and comment on this in terms of the interfaces between the superconducting leads and non-superconducting junction and the carriers in the junctions are itself.
Furthermore, we show that several fundamentally different junctions can be formed in a single device.
Apart from the before-mentioned technological applications, this opens possibilities to investigate the nature of the superconducting state in magic-angle twisted bilayer graphene.

F.K. de Vries et al. ArXiv:2011.00011 (2020)