ESPCI web site
October 16 at 2:00 pm (Paris time)
Room Boreau, building C, 2nd floor, 10 rue Vauquelin, ESPCI
Tuning multiband superconductivity and quantum geometry in moiréflatband systems
Superconductivityin flatband systems has attracted tremendous attention in condensed matterphysics. Alternating twisted multilayer graphene presents a compellingmultiband system, with a coexistence of Dirac bands and flat bands, forexploring superconductivity. In this talk, I will present an observation of unconventionalsuperconducting behaviours in the alternating twisted quadralayer graphene. Wesystematically quantify individual carrier density contributions for both thedispersive bands and the flat bands from Dirac spectroscopy. We furtherestimate the flat-band Fermi velocity and superfluid stiffness via criticalcurrent measurements. Our results demonstrate an electric field–tunablecoupling strength within the superconducting phase, revealing unconventionalproperties with vanishing Fermi velocity and large superfluid stiffness. Thesephenomena, attributed to substantial quantum metric contributions mediated byDirac band hybridization, offer new insights into the mechanisms underlyingunconventional flatband superconductivity in moiré systems.
