Electron momentum density of hexagonal cadmium studied by Compton scattering

The directional electron momentum density distributions (Compton profiles) of single‐crystal cadmium have been measured in transmission and reflection experimental geometries using high‐energy (662 keV) gamma radiation from a 137Cs isotope source. Profiles along the [100] and [110] directions in reciprocal space were measured in both geometries, whereas only the transmission geometry was used for the measurements along the [001] direction. The experimental data have been compared with corresponding theoretical KKR semi‐relativistic calculations. The directional difference profiles, both experimental and theoretical, show, similarly to other hexagonal systems, very small anisotropy of the electron momentum density in hexagonal cadmium, about 0.3%, i.e. less than half of that presented in the literature for cubic systems. Minor discrepancies between KKR calculations and experiment probably occur due to the necessity to introduce an anisotropic electron–electron correlation correction. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)