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Phys. Rev. B 70, 155411 (2004) [7 pages]

Surface structure of ultrathin copolymer films of ferroelectric vinylidene fluoride (70%) with trifluoroethylene (30%) on graphite

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Lei Cai1, Hongwei Qu1,*, Chenxi Lu1, S. Ducharme2, P. A. Dowben2, and Jiandi Zhang1,†
1Department of Physics, Florida International University, Miami, Florida 33199, USA
2Department of Physics and Astronomy and Center for Materials Research and Analysis, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA

Received 7 June 2004; published 26 October 2004

The structure and local structural distortions, through the polarization manipulation, of crystalline films of ferroelectric vinylidene fluoride (70%) with trifluoroethylene (30%) [P(VDF-TrFE)] copolymer on graphite were studied by scanning tunneling microscopy (STM). A quasispiral twist in CC bonds with rotations about the polymer chain axis was observed by high-resolution STM, indicating a surface relaxation of the strained copolymer films. Such a relaxation behavior appears to be linked to the observed local dipole rotations accompanied by the reversal of the local polarization with biasing the STM tip. A structure model is proposed based upon the observations.

© 2004 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.70.155411
DOI:
10.1103/PhysRevB.70.155411
PACS:
68.55.Jk, 77.84.Jd, 82.37.Gk, 77.22.Ej

*Current address: Department of Electrical and Computer Engineering, the University of Florida

†Author to whom correspondence should be addressed. Electronic address: zhangj@fiu.edu

 
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