Seminars Archive

Electron-Phonon coupling in two dimensions: Be(0001)

Abstract
The coupling between conduction electrons and phonons is one of the most important interactions in solids. As an example, this mechanism is responsible for the occurance of a superconducting BCS-ground state and of Kohn anomalies (phonon softening). In low dimensions, the effects of the interactions are even more pronounced and give rise to instabilities of the ground state. The (0001)-surface of Be provides an ideal testing ground for the study of this coupling in two dimensions: a nearly free-electron-like surface state, which dominates the density of states at the Fermi energy, in line with a high Debye temperature allow to follow the evolution of the electron spectral function over a large energy scale. In this talk, high-resolution photoemission spectra will be presented which reveal drastic changes of the free-electron behaviour due to the interactions. The spectral function, measured in this experiment, serves as fingerprint and is compared to simple model calculations within the Fermi liquid theory. All necessary parameters are directly taken from the experiment.