TY - JOUR
T1 - Bend-Induced Ferroelectric Domain Walls in α-In2Se3
AU - Han, Edmund
AU - Nahid, Shahriar Muhammad
AU - Rakib, Tawfiqur
AU - Nolan, Gillian
AU - Ferrari, Paolo F.
AU - Hossain, M. Abir
AU - Schleife, André
AU - Nam, Sung Woo
AU - Ertekin, Elif
AU - van der Zande, Arend M.
AU - Huang, Pinshane Y.
N1 - Publisher Copyright:
© 2023 American Chemical Society.
PY - 2023/4/25
Y1 - 2023/4/25
N2 - The low bending stiffness of atomic membranes from van der Waals ferroelectrics such as α-In2Se3 allow access to a regime of strong coupling between electrical polarization and mechanical deformation at extremely high strain gradients and nanoscale curvatures. Here, we investigate the atomic structure and polarization at bends in multilayer α-In2Se3 at high curvatures down to 0.3 nm utilizing atomic-resolution scanning transmission electron microscopy, density functional theory, and piezoelectric force microscopy. We find that bent α-In2Se3 produces two classes of structures: arcs, which form at bending angles below ∼33°, and kinks, which form above ∼33°. While arcs preserve the original polarization of the material, kinks contain ferroelectric domain walls that reverse the out-of-plane polarization. We show that these kinks stabilize ferroelectric domains that can be extremely small, down to 2 atoms or ∼4 Å wide at their narrowest point. Using DFT modeling and the theory of geometrically necessary disclinations, we derive conditions for the formation of kink-induced ferroelectric domain boundaries. Finally, we demonstrate direct control over the ferroelectric polarization using templated substrates to induce patterned micro- and nanoscale ferroelectric domains with alternating polarization. Our results describe the electromechanical coupling of α-In2Se3 at the highest limits of curvature and demonstrate a strategy for nanoscale ferroelectric domain patterning.
AB - The low bending stiffness of atomic membranes from van der Waals ferroelectrics such as α-In2Se3 allow access to a regime of strong coupling between electrical polarization and mechanical deformation at extremely high strain gradients and nanoscale curvatures. Here, we investigate the atomic structure and polarization at bends in multilayer α-In2Se3 at high curvatures down to 0.3 nm utilizing atomic-resolution scanning transmission electron microscopy, density functional theory, and piezoelectric force microscopy. We find that bent α-In2Se3 produces two classes of structures: arcs, which form at bending angles below ∼33°, and kinks, which form above ∼33°. While arcs preserve the original polarization of the material, kinks contain ferroelectric domain walls that reverse the out-of-plane polarization. We show that these kinks stabilize ferroelectric domains that can be extremely small, down to 2 atoms or ∼4 Å wide at their narrowest point. Using DFT modeling and the theory of geometrically necessary disclinations, we derive conditions for the formation of kink-induced ferroelectric domain boundaries. Finally, we demonstrate direct control over the ferroelectric polarization using templated substrates to induce patterned micro- and nanoscale ferroelectric domains with alternating polarization. Our results describe the electromechanical coupling of α-In2Se3 at the highest limits of curvature and demonstrate a strategy for nanoscale ferroelectric domain patterning.
KW - bending
KW - ferroelectric domain wall
KW - flexoelectricity
KW - transmission electron microscopy
KW - van der Waals ferroelectric
KW - α-InSe
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U2 - 10.1021/acsnano.3c01311
DO - 10.1021/acsnano.3c01311
M3 - Article
C2 - 37057994
AN - SCOPUS:85153803575
SN - 1936-0851
VL - 17
SP - 7881
EP - 7888
JO - ACS Nano
JF - ACS Nano
IS - 8
ER -