Superconducting Quantum Interference Devices in Magic-Angle Twisted Bilayer Graphene

Magic-Angle Twisted Bilayer Graphene hosts a range of physical phenomena that can be tuned by electrostatic doping [1]. We have realized Josephson junctions on this material by combining gate-defined regions tuned to superconducting or insulating phases [2]. This has shown the potential of the material to become a platform for versatile superconducting devices [2, 3]. Here we take the next step in terms of device complexity and show data from a Superconducting Quantum Interference Device (SQUID) defined in Magic-Angle Twisted Bilayer Graphene. We characterize the device and use it to directly measure the current-phase relation of one of the junctions in the ring, a measurement impossible to realize with a single junction.

[1] Cao, Y. et al. Unconventional superconductivity in magic-angle graphene superlattices. Nature 556, 43–50 (2018)

[2] de Vries, F.K. et al. Gate-defined Josephson junctions in magic-angle twisted bilayer graphene. Nat. Nanotechnol. 16, 760–763 (2021)

[3] Rodan-Legrain, et al. Highly tunable junctions and non-local Josephson effect in magic-angle graphene tunnelling devices. Nat. Nanotechnol. 16, 769–775 (2021)