DFT-based calculations of the magnetic hyperfine interactions at Cd sites in RCd (R = rare earth) compounds with the FP-LAPW ELK code

L S Maciel,V C Gonçalves,G A Cabrera-Pasca,A Burimova,A W Carbonari,R N Saxena,L F D Pereira,T S N Sales,W L Ferreira

doi:10.1063/9.0000161

Abstract

In the work here reported, we have calculated magnetic hyperfine interactions in rare-earth (R) intermetallic compounds by using the free open-source all-electron ELK code. The RCd (R = Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) series was chosen as a test system because an almost complete set of experimental data on the hyperfine parameters at Cd sites was acquired through the time differential perturbed angular correlation (TDPAC) spectroscopy as previously reported. Moreover, results on magnetic hyperfine field (Bhf) from WIEN2k code were also reported allowing a qualitative comparison analysis. We emphasize that the utilized version of ELK accounted for the contact field only. Yet, as it is the only contribution expected for Cd site in RCd compounds, the calculated Bhf values are in reasonable agreement with the experimental results. The Spin-orbit coupling when taken into account led to a decrease in deviation from experimental data. Addition, the Hubbard-like term was revealed crucial in order to make Bhf predictions for CeCd, suggesting that this behavior may be associated with a weaker 4f electron localization in Ce.

Highlights

INTRODUCTIONMagnetic materials present singular properties which have their origin at the atomic level where the electronic contributions play a crucial role throughout
In order to investigate the hyperfine interactions in the RCd series, the theoretical spin band structure calculations based on the density functional theory (DFT) formalism have been performed with the full potential linearized augmented plane wave (FP-LAPW)16 plus local orbitals, as implemented in the ELK code
It is important to mention that for CeCd, considering only spin-orbit coupling in the calculations, the difference was about 63% higher when compared with BEhfXP

Summary

INTRODUCTION

Magnetic materials present singular properties which have their origin at the atomic level where the electronic contributions play a crucial role throughout. The main feature of rare-earth elements is that the orbital magnetic contribution is strong in relation to spin and intensively varies with the number of 4f electrons Such RCd compounds (where Cd is a nonmagnetic atom) crystallize in the high-symmetry cubic CsCl - type of structure (space group Pm-3m), which favors the experimental magnetic hyperfine interaction investigation due to the absence of electric quadrupole interactions as well as reduces the time for first-principles calculations. It is known that there is a shortcoming in the electronic band structure codes for Bhf calculations.14 They are state-of-the-art of ab initio calculation in solids and the Fermi Contact contribution has evaluated better than the orbital contribution to Bhf .15. Where Bc is the Fermi contact term, Borb is the field associated with the on-site orbital moment and Bsp is the dipolar field from the onsite spin density

FIRST-PRINCIPLES CALCULATIONS

RESULTS AND DISCUSSION

SUMMARY