|Michael Sullivan Online|
Multiscale kinetic model for polarization switching in ferroelectric polymer thin films
Rajeev Ahluwalia, Michael B. Sullivan, David J. Srolovitz, Jian Wei Zheng, and Alfred C. H. Huan
Materials Theory and Simulation Laboratory, Institute of High Performance Computing, A*STAR (Agency for Science, Technology and Research), Singapore 117528, Singapore
Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore 117602, Singapore
Computational Materials Science and Engineering Programme, Institute of High Performance Computing, A*STAR (Agency for Science, Technology and Research), Singapore 117528, Singapore
Department of Physics, Yeshiva University, New York, New York 10033, USA
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637616, Singapore
(Received 10 March 2008; revised 5 June 2008; published 12 August 2008)
Phys. Rev. B, 2008, 78, 054110.
Polarization switching in ferroelectric polymers is studied using a multiscale framework. A continuum Landau-Ginzburg-Devonshire model for a first-order phase transition is parametrized for ideal all trans chains of P(VDF-TrFE) (70:30) copolymers using data obtained from molecular-dynamics (MD) simulations. Thermal fluctuations and kinetics are accounted for by using a time-dependent Ginzburg-Landau model where the length and time scales, as well as the thermal noise amplitude, are also set from MD simulations. This method is used to investigate the nature of polarization switching in ferroelectric polymers and to test recent claims that ultrathin ferroelectric polymer films undergo intrinsic switching. Our simulations show that for a defect-free system, domain nucleation due to thermal fluctuations prevents homogeneous switching of the polarization, even at very small thicknesses. However, this nucleation does not substantially decrease the coercive field compared to the intrinsic value.