Correlated insulator behaviour at half-filling in magic-angle graphene superlattices
This companion paper reports that twisted bilayer graphene at the magic angle exhibits insulating states at half-filling of the flat moire bands, where simple band theory would predict a metal. The authors interpret these as Mott-like correlated insulators arising from strong electron-electron interactions in the nearly flat bands. The result demonstrates that twist-angle engineering can drive graphene into strongly correlated electronic phases.