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 - Funding Information:
This work was primarily supported by NSF-MRSEC under Award Number DMR-1720633. This work was also supported by the Air Force Office of Scientific Research under grant No. FA9550-20-1-0302 and the Office of Naval Research under grant No. N00014-18-1-2605. This work was carried out in part in the Materials Research Laboratory Central Facilities at the University of Illinois, where electron microscopy support was provided by Changqiang Chen and Honghui Zhou. The authors acknowledge the use of facilities and instrumentation supported by NSF through the University of Illinois Materials Research Science and Engineering Center DMR-1720633. Computational resources were funded by the National Science Foundation under Award Numbers DMR-1555278 and DMR-1720633. This research used resources of the Oak Ridge Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC05-00OR22725.
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 -