Investigation of local magnetic properties of CeCd as a function of the unit cell volume by means of first principles calculations

Abstract

In the work here reported magnetic hyperfine field (Bhf) at Cd site as well as the cerium magnetic moment (m-Ce) were calculated from simulation of the CeCd compound in many different unit cell volumes. Results are compared with the experimental values of Bhf (5.10 T) obtained with Perturbed Angular Correlation spectroscopy measurements [1] and m-Ce from magnetization measurements. The electronic structure calculations of the CeCd cubic cells (under normal conditions the space group is Pm-3m) were performed using density functional theory implemented on ELK and WIEN2k codes with “full-potential linearized augmented plane wave” method and the local density or generalized gradient approximations to estimate exchange-correlation energy. Three methodologies were carried out in our simulations: just spin polarized (SP); spin-orbit coupling (SO); and, SO plus ad hoc U parameter to treat the strong correlation in the cerium 4f shell. The cell energy (CE), m-Ce and Fermi-contact contribution (BFc) of Cd-Bhf from electrons (labelled core and valence) inside the atomic spheres and others quantities were calculated for volume fractions varying from -14% to 5% of the experimental unit cell volume, in steps of 1%. The smallest energy and bestest Cd-Bhf agreement were reached when the volume is compressed by 12%. Results are discussed in terms of Ce-4f electron (de)localization and its strong correlation as well as hybridization effects between Cd and Ce observed through density of states plots to understand the dependence of Cd-BFc with the compression and relaxation of the cell. A brief comparison of Cd-BFc for 3 the methodologies and m-Ce and Cd-BFc versus volume (SP calculation) from WIEN2k are presented.