Emergent ferromagnetism near three-quarters filling in twisted bilayer graphene

Abstract

Twisted bilayer graphene goes magnetic When two layers of graphene in a bilayer are twisted with respect to each other by just the right, “magic,” angle, the electrons in the system become strongly correlated. As the electronic density is tuned by gating, the system goes through several exotic phases, including superconductivity. Now, Sharpe et al. show that, at a particular electronic density, magic-angle graphene becomes magnetic (see the Perspective by Pixley and Andrei). The finding is supported by the observation of a large anomalous Hall effect. Science , this issue p. 605 ; see also p. 543