Dielectric anomalies in Ferroelectric nanostructures (Phys. Rev by gcpCOvQ

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									                         Modelling and Designing Ferroelectrics
                       with Defects and in Two-dimensional Forms
                 Laurent Bellaiche, University of Arkansas, DMR 0404335
Ferroelectric thin films are of increasing interest due to their unique potential for the next
generation of functional nanoscale devices with superior properties. The most important
issue in such devices is how to control the polarization (which arises from the formation of
electric dipoles). First-principles calculations confirmed a recent, exciting experimental
finding, namely that such polarization can be manipulated by deforming the ferroelectric film
on a picosecond time scale. These first-principles simulations also provided the microscopic
origin of this anomalous dynamical coupling between polarization and picosecond time-scale
strain pulses, that is a ``slow breathing’’ of dipolar inhomogeneities. [Phys. Rev. Lett. 101,
197602 (2008)]




  Snapshots at different times of the dipole pattern in a ferroelectric film subject to an ultrafast strain
  pulse. A nanobubble (in which the dipoles are along a direction opposite to that of the dipoles
  located outside this nanobubble) changes its size, which is the discovered process allowing an
  unusual control of polarization.
             Modelling and Designing Ferroelectrics
           with Defects and in Two-dimensional Forms
        Laurent Bellaiche, University of Arkansas, DMR 0404335

Broader impact:
   6 graduate students (including two of female gender) and 7 research
    associates (including two of female gender) contributed to the works
    associated with this grant.
   Mrs Laura Walizer received her Ph.D. of Physics in Spring 2009.
   Dr. Inna Ponomareva became Assistant Professor at The University of South
    Florida in Spring 2009.
   Collaborations with international groups, and strongly involving students and
    research associates, occurred.
   The P.I. spent one day with students in an elementary school in Fall 2008.
   The P.I.’s group and collaborators gave several invited talks at international
    conferences.
   An invited review article on complex dipolar structures was written and
    published in a special issue of Journal of Materials Science.

								
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