Electron momentum density in yttrium

TL;DR

This study combines experimental measurements and theoretical calculations to analyze electron momentum density in yttrium, revealing anisotropies and correlation effects consistent with band structure predictions.

Contribution

It provides a comprehensive analysis of electron momentum density in yttrium using combined experimental and relativistic theoretical approaches, highlighting correlation effects.

Findings

Experimental anisotropy matches theoretical band structure.

Electron-electron correlations are observed in both experiments.

Electron-positron correlations are not detected in positron annihilation data.

Abstract

A simultaneous analysis of high-resolution directional Compton profiles and two-dimensional angular correlation of positron annihilation experimental data has been performed by studying both a directional anisotropy of measured spectra and reconstructed densities. The results were compared with theoretical fully-relativistic augmented plane-wave calculations with and without including correlation effects. Estimated symmetry selection rules have allowed us to establish some values of Fermi momenta. Both experiments show exactly the same shape of the anisotropy of the momentum densities, in agreement with the band structure results. In the positron annihilation data electron-positron correlations are not seen while in both experiments electron-electron correlations are observed.