Photoemission band symmetries and dipole active modes of crystalline films of vinylidene fluoride (70%) with trifluoroethylene (30%) across the ferroelectric transition(s)
Year: 2000
Type: article
Abstract: The symmetry of the occupied electronic bands of crystalline films of vinylidene fluoride (70%) with trifluoroethylene (30%) and the vibrational dipole modes are identified using angle resolved photoemission and high resolution electron energy loss respectively. The symmetry of the occupied valence bands is preserved across the surface `ferroelectric' phase transition. The temperature dependent changes in the electronic structure occur primarily in the conduction band and are accompanied by a surface dipole reorientation and a surface Brillouin zone doubling across the surface transition, thus these results strongly support a first order transition with a uniaxial polarization direction in these crystalline ferroelectric polymer films. There is compelling evidence that this surface phase transition is an improper ferroelectric transition and discontinuous.
Authors: Jaewu Choi, S-J Tang, P T Sprunger, P A Dowben, V M Fridkin, A V Sorokin, S P Palto, N Petukhova, S G Yudin
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2053376903