Abstract
Density functional theory calculations with an on-site Coulomb repulsion term reveal competing ground states in (111)-oriented superlattices with -type interfaces, ranging from spin, orbitally polarized (with selective , , or occupation), Dirac point Fermi surface, to charge-ordered flat band phases. These phases are steered by the interplay of (i) Hubbard , (ii) quantum well thickness, and (iii) crystal field splitting tied to in-plane strain. In the honeycomb lattice bilayer under tensile strain, inversion symmetry breaking drives the system from a ferromagnetic Dirac point (massless Weyl semimetal) to a charge-ordered multiferroic (ferromagnetic and ferroelectric) flat band massive (insulating) phase. With increasing quantum well thickness an insulator-to-metal transition occurs.
- Received 29 March 2013
DOI:https://doi.org/10.1103/PhysRevLett.111.126804
© 2013 American Physical Society