Band Structure of CaCd and CaTl and the Knight Shift of 113Cd- and 205Tl-NMR in the System CaCd1-x Tlx

Abstract

The energy bands of ordered CaCd and CaTl have been calculated by the nonrelativistic augmented plane wave (APW) method. The electron structure in the system CaCd1-xTlx is deduced from these calculations by using the rigid band model for the phases with 0<x<1. The band structures of CaCd and CaTl are similar to the valence bands of other phases of the CsCl-type. From the energy eigenvalues the electronic density of states curve, the partial densities of states curves, and the Fermi energy have been obtained. For states near the Fermi surface the spin density at the position of the Cd- and Tl-nuclei has been determined. The Knight shift Ks of the 113Cd-NMR and the 205Tl-NMR in the system CaCd1-xTlx has been calculated as a function of x. The slope of the curve Ks (x) for the Cd-NMR is equal for experimental and theoretical results. The absolute value of the calculated Knight shift is about a factor of 1.4 too small. Only the direct term to the Knight shift has been calculated. Relativistic effects have been included by a scale factor. It has not been possible to explain the shape of the function (2) for the Tl-NMR, since a full relativistic APW calculation is necessary for CaTl