Electron Momentum & Fermi Surface Studies
Overview
Investigation of electron momentum distributions and Fermi surface topologies in metals and semi-metals using two-photon annihilation of electron–positron pairs. This research provides insight into the electronic band structure and Fermi surface properties of condensed matter systems.
Key techniques include Doppler-broadened positron annihilation spectroscopy and angular correlation of annihilation radiation (ACAR).
Electron Momentum Density in Aluminum
Abstract
Doppler-broadened positron annihilation spectroscopy has been employed to study the electron momentum density in aluminum. The Compton profile measurements provide direct information about the valence electron distribution and its deviation from the free-electron model.
Key Results
The experimental Compton profiles show good agreement with theoretical calculations based on the augmented plane wave method. Small but significant deviations from the free-electron sphere are observed, reflecting the influence of the periodic potential on the electron momentum distribution.
Fermi Surface Studies of Copper by Two-Photon Annihilation
Abstract
A two-photon annihilation study of the Fermi surface in high-purity copper single crystals has been carried out using angular correlation of annihilation radiation (ACAR). The measured momentum density distributions are compared with band-structure calculations to elucidate the details of the Fermi surface topology.
Key Results
The ACAR profiles reveal clear signatures of the electron-positron momentum correlation. The Fermi surface features are consistent with local-density approximation calculations, with deviations attributed to electron-positron correlation effects.