Finite curvature-mediated ferroelectricity.
We demonstrate that ferroelectric (FE) polarizations oriented along the finite thickness direction in ultrathin films are enhanced by the introduction of extreme curvature, thereby suppressing the finite-size-driven evolution of the FE phase transition temperature T(C). The measured responses within individual nanoshells possess magnitudes nearly three times that for their planar counterparts while exhibiting finite curvature-dependent offsets in FE switching hystereses. In stark contrast to the expected scaling of a depression of T(C) with inverse thickness, results based on modified Landau-Ginzburg model calculations indicate geometric curvature-driven polarization gradients in ultrathin films result in significant increases in T(C).
Nonnenmann
Stephen S
SS
Department of Materials Science and Engineering, DrexelUniversity, Philadelphia, Pennsylvania 19104, USA.
Leaffer
Oren D
OD
Gallo
Eric M
EM
Coster
Michael T
MT
Spanier
Jonathan E
JE