A rigid band model for the “crystal field” at a dy 3+ impurity in Cu

Abstract

A calculation of the b4 and b6 crystal field parameters for Dy 3+ impurities in Cu is presented within a rigid band model scheme. In our model the “crystal field” results from the direct and exchange contribution due to the Coulomb interaction of the 4f electrons with those in the band states. These states are obtained with the augmented plane wave method, which are assumed to penetrate the ion. The contributions to b4 and b6 obtained at different k-points within the Brillouin zone are examined and we find that for almost all band states the exchange contribution dominates the direct one. We obtain crystal field parameters with the right sign and order of magnitude, which result from a balance between the fully occupied bands of d character and the half occupied s band.