Ferroelectric materials are characterized by a spontaneous polarization that can be switched by external electric field. This property is important for various technological applications such ferroelectric random access memories. However, when

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Enhanced Ferroelectric Stability by Interface
Engineering
A. Gruverman and E. Y. Tsymbal (Nebraska MRSEC)
C.-B. Eom (University of Wisconsin) X. Pan
(University of Michigan)
Ferroelectric materials are characterized by a
spontaneous polarization that can be switched by
external electric field. This property is
important for various technological applications
such ferroelectric random access memories.
However, when ferroelectric film thickness is
reduced down to a nanoscale the ferroelectric
polarization may become unstable due to strong
depolarization fields and interface effects.
Nebraska MRSEC researchers in collaboration with
their colleagues at Universities of Wisconsin and
Michigan have predicted and demonstrated that
interface engineering may be efficiently used to
stabilize ferroelectric polarization at the
nanoscale. Using sophisticated first-principles
calculations and advanced fabrication and
characterization techniques the researchers
showed that deposition of a two-unit cell thick
non-ferroelectric strontium titanate layer at the
interface enhances the polarization of
ferroelectric barium titanate layer, making it
switchable by an applied electric filed. This
discovery provides a new insight into the
switching and retention behavior of thin-film
ferroelectric materials and paves the way to
atomic scale property engineering in
ferroelectric-based electronic devices. This work
was partly supported by the Nanoelectronics
Research Initiative of Semiconductor Research
Corporation.
Experimental observation of enhanced polarization
of a barium titanate thin film. Left images have
the same contrast indicating that polarization of
barium titanate is not switched by electric
field. Right images have different contrast
indicating that the interface engineered film can
be switched by an electric field.
These programs are supported by the National
Science Foundation, Division of Materials
Research, Materials Research Science and
Engineering Program, Grant 0820521.