Observation of Vortex Domains in a Two-Dimensional Lead Iodide Perovskite Ferroelectric

Topological defects,
such as vortices and skyrmions, provide a
wealth of splendid possibilities for new nanoscale devices because
of their marvelous electronic, magnetic, and mechanical behaviors.
Recently, great advances have been made in the study of the ferroelectric
vortex in conventional perovskite oxides, such as BaTiO3 and BiFeO3. Despite extensive interest, however, no intriguing
ferroelectric vortex structures have yet been found in organic–inorganic
hybrid perovskites (OIHPs), which are desirable for their mechanical
flexibility, ease of fabrication, and low acoustical impedance. We
observed the robust vortex–antivortex topological configurations
in a two-dimensional (2D) layered OIHP ferroelectric (4,4-DFPD)2PbI4 (4,4-DFPD is 4,4-di­fluoro­piper­idinium).
This provides future directions for the study of perovskites and makes
it a promising alternative for nanoscale ferroelectric devices in
medical, micromechanical, and biomechanical applications.