Condensed Matter Physics Seminar
Electron Phonon Coupling in Quasi-One Dimensional Systems
Department of Physics and Astronomy
University of Nebraska
The electron phonon coupling in metal chains grown of furrowed surfaces and polymer chains are compared. A lattice-stiffening transition is observed near 230 K in corrugated "chain like" gadolinium structures formed on furrowed metal substrates (Mo(112) and W(112)) and a similar transition is observed in the ferroelectric polymer polyvinylidene fluoride with trifluorethylene at 160 K. This transition is evident from the change in the effective Debye temperatures. Given the similarities between the lattice stiffening transition observed in Gd chains and polymer chains, we propose that a significant dipole-dipole coupling interaction term within the chain is key, is spite of the fact that these systems are hugely dissimilar. The use of a lateral interaction dipole-dipole term, with pronounced dipoles oriented along the surface normal, is indicated in low dimensional surface structures and is very similar to the insulating polymer chains where intramolecular dipole-dipole interactions are quite pronounced, but are weak between the chains. The relationship to local point group symmetry and band structure with vibronic coupling will be discussed.
Thursday, December 1, 2005
Gant Science Complex
(The seminar is followed by coffee/tea, cookies, and an informal discussions.)