Electron momentum density of hexagonal zinc studied by Compton scattering

Abstract

We have measured the directional Compton profiles of a single crystal of hexagonal zinc along the [00·1], [10·0], [11·0] and [11·1] directions using high-energy (662 keV) gamma radiation from a 137Cs isotope source. The experimental data have been compared with the corresponding theoretical Korringa-Kohn-Rostoker semi-relativistic calculations. The theory slightly overestimates the electron momentum densities at low momenta regions for all measured profiles. The directional difference profiles, both experimental and theoretical, show very small anisotropy of the electron momentum density in hexagonal zinc, at most half of that presented in the literature for cubic systems.

Electron momentum density of hexagonal cadmium studied by Compton scattering

“…This property can be expected based on purely geometrical grounds. In fact, similarly small anisotropy has recently been observed in hexagonal zinc [12]. In Fig.…”

“…The KKR theory seems to reproduce the experiment quite well in the whole momentum region. The usual surplus of theoretical values above the experimental values at the origin of the CPs observed in previous Compton experiments on various materials [12,[27][28][29][30][31][32] is not visible after subtraction of additional background. Usually, this kind of difference between experiment and theory is attributed to electron correlation effects, which are not well incorporated in the theory.…”

“…The band-structure theory, however, does not give a good description of the changes in the lattice properties of Cd and Zn observed under pressure. Our earlier studies of the Compton scattering from zinc [12] also called for an improvement of the theory of hexagonal metals. Therefore, experimental input concerned with the electronic structure of these metals is of relevance to theory.…”

Electronic Origin of the Structural Anomalies of Zinc and Cadmium

“…Directional Compton profiles for the most relevant directions of hcp metals were previously recorded for zinc19,20, magnesium20 and cadmium20 with medium resolution (0.4 a.u. ), using a γ ‐ray source.…”

Different ways of dealing with Compton scattering and positron annihilation experimental data

“…Because reconstruction of densities from plane projections requires a lot of profiles, in the case of Compton scattering spectra their analysis was performed mainly for J(p z ) (e.g. [28,32]). However, development of synchrotron sources and the possibility of measuring many high-resolution Compton profiles makes this technique promising for the future [33,34], the more so as there is even pos-sibility of measuring directly 3D electron densities using (γ,eγ) technique [35] (up to now limited mainly due to statistics).…”