Alternating twisted multilayer graphene: generic partition rules, double flat bands, and orbital magnetoelectric effect

Recently the alternating twisted trilayer graphene is discovered to exhibit unconventional superconductivity, which motivates us to study the electronic structures and possible correlation effects for this class of alternating twisted multilayer graphene (ATMG) systems. In this work we consider generic ATMG systems with M-L-N stacking configurations, in which the M (L) graphene layers and the L (N) layers are twisted by an angle theta (-theta). Based on analysis from a simplified k center dot p model approach, we derive generic partition rules for the low-energy electronic structures, which exhibit various band dispersions including two pairs of flat bands and flat bands co-existing with various gapless Fermionic excitations. For a mirror-symmetric ATMG system with doubled flat bands, we further find that Coulomb interactions may drive the system into a state with intertwined electric polarization and orbital magnetization orders, which can exhibit an interaction-driven orbital magnetoelectric effect.

Automated summary

Recently, unconventional superconductivity has been discovered in alternating twisted trilayer graphene, which has motivated research on the electronic structures and possible correlation effects in this class of alternating twisted multilayer graphene systems. Through analysis, generic partition rules for the low-energy electronic structures have been derived, which include flat bands and gapless Fermionic excitations.