Moiré polar vortex, flat bands, and Lieb lattice in twisted bilayer BaTiO 3 .

Autor: Lee S; Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA., de Sousa DJP; Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA., Jalan B; Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA., Low T; Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA.; Department of Physics, University of Minnesota, Minneapolis, MN 55455, USA.
Jazyk: angličtina
Zdroj: Science advances [Sci Adv] 2024 Nov 22; Vol. 10 (47), pp. eadq0293. Date of Electronic Publication: 2024 Nov 20.
DOI: 10.1126/sciadv.adq0293
Abstrakt: Through first-principles calculations based on density functional theory, we investigate the crystal and electronic structures of twisted bilayer BaTiO 3 . Our findings reveal that large stacking fault energy leads to a chiral in-plane vortex pattern that was recently observed in experiments. We also found nonzero out-of-plane local dipole moments, indicating that the strong interlayer interaction might offer a promising strategy to stabilize ferroelectric order in the two-dimensional limit. The vortex pattern in the twisted BaTiO 3 bilayer supports localized electronic states with quasi-flat bands, associated with the interlayer hybridization of oxygen p z orbitals. We found that the associated bandwidth reaches a minimum at ∼19 twisting, configuring the largest magic angle in moiré systems reported so far. Further, the moiré vortex pattern bears a notable resemblance to two interpenetrating Lieb lattices and the corresponding tight-binding model provides a comprehensive description of the evolution the moiré bands with twist angle and reveals the topological nature.
Databáze: MEDLINE