Superconductivity in Twisted Trilayer Graphene Aligned to hBN

Empirical evidence indicates that superconductivity in twisted bilayer graphene (TBG) is suppressed when one of the graphene layers is closely aligned to an encapsulating hexagonal boron nitride (hBN) layer. Theoretical models of TBG and twisted trilayer graphene (TTG) suggest sublattice symmetry breaking is detrimental to superconductivity, potentially accounting for this observation. Here we show that, unlike aligned TBG, superconductivity can persist in TTG when aligned to hBN. Using lateral force microscopy (LFM) to characterize the strength of hBN alignment during fabrication, we examine the transport properties of TTG devices with varying degrees of TTG-hBN alignment and explore the subtle interplay between sublattice symmetry breaking, the TTG bandstructure, and the persistence of superconductivity in these devices.