Description
The first experimental realization of the moiré effect in bilayer graphene at the “magic” 1.1° [1] has led to the discovery of remarkable phenomena, including unconventional superconductivity and the quantum anomalous Hall effect. Twisted two-dimensional heterostructures are emerging as an active field for exploration of unexplored physical phenomena. Recently, twisted oxide heterostructures have been experimentally realized [2, 3], and due to strong interlayer interactions and lateral strain modulation moiré polar vortices and antivortices have been predicted. Here, using first-principles calculations based on density functional theory, we investigate the structural and electronic properties of twisted bilayer BaTiO3/SrTiO3 for various stacking configurations and twist angles. Our results show that lattice reconstruction leads to in-plane polar vortex patterns with opposite chirality between the layers and pronounced shear-strain modulation. In addition, non-zero out-of-plane local dipole moments are observed, giving rise to alternating polar domains. Furthermore, we find flat valence band features and enhanced charge localization, are strongly modulated by the twist angle and arise from interlayer bonding effects. Moreover, the charge density difference and quantitative Bader charge analysis are calculated to give insight into the charge redistribution between the two layers. Overall, our results demonstrate that the twist angle serves as an effective parameter for tuning the intertwined structural and electronic properties of oxide heterostructures. By establishing a direct link between structural symmetry breaking and charge localization, this work provides a framework for designing next-generation multifunctional devices.
[1] Nature Physics 6, 109–113 (2010).
[2] Nature 626, 529–534 (2024).
[3] Nature. Communications 15, 10915 (2024).
| I am the presenting author | Yes |
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