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O: Fachverband Oberflächenphysik

O 109: Focus Session: Proximity Effects in Epitaxial Graphene II

O 109.5: Topical Talk

Friday, March 22, 2024, 11:45–12:15, MA 141

Superconducting quantum devices in twisted graphene layers — •Klaus Ensslin — Physics Department, ETH Zurich

We realize gate-defined quantum devices on magic-angle twisted bilayer graphene. Different correlated states can be tuned by gate voltages, including superconducting states, band insulators and correlated insulators. This way we have fabricated Josephson junctions [1] as well as a SQUID with tunable symmetry [2]. A novel entirely gate-induced ring geometry [3] was employed to detect the Little-Parks effect [4] where the state of the ring as well as that one of the confining potential inside and outside of the ring became tunable. These experiments pave the way to more complex graphene quantum devices involving superconductivity and possibly Coulomb blockade. These experiments have been done in collaboration with Peter Rickhaus, Fokko de Vries, Elias Portoles, Giulia Zheng, Marta Perego, Alexandra Mestre Tora, Shuichi Iwakiri and Thomas Ihn.

[1] de Vries et al. , Nature Nano 16, 760 (2021) [2] Portolés et al., Nature Nano 17, 1159 (2022) [3] Iwakiri et al., Nano Lett. 22, 6292 (2022) [4] Iwakiri et al., arXiv:2308.07400

Keywords: graphene, superconductivity, devices