Seminar – Glenn Wagner – Oxford University

Kekule spiral order in twisted bilayer graphene

Twisted bilayer graphene has attracted a lot of attention due to the presence of correlated insulators proximate to superconductivity. In this talk I will present a new proposal for the nature of the correlated insulators. This order, which we dub the ‘incommensurate Kekule spiral’ (IKS) order, spontaneously breaks both the emergent valley-charge conservation and moire translation symmetries. The IKS state emerges as the ground state in detailed self-consistent Hartree-Fock calculations at any non-zero integer filling of the moire unit cell. I will discuss the phenomenological and microscopic properties of this order and argue that our findings are consistent with all experimental observations reported so far, suggesting a unified explanation of the global phase diagram of twisted bilayer graphene in terms of the IKS order.