Correlated electronic structures and magnetic properties of cerium monopnictides

Abstract

The electronic structures in cerium monopnictides CeX (X = N, P, As, Sb, Bi) have been systematically investigated using the DFT + DMFT method. We first investigate the geometric structures of the CeX. The results regarding the lattice parameter a, the bond length of Ce-X ions, the electronegativity of X ions, and the ion radius of X ions indicate that CeN is the most anomalous among them. This implies that the physical properties of CeN differ from those of other CeX (X = P, As, Sb, Bi) compounds. Based on this, we further investigate Ce-4f electrons’ behavior through the momentum-resolved spectral functions of CeX, the densities of states of Ce-4f_5/2 and Ce-4f_7/2 orbitals, and the Fermi surfaces. All these results present metal in CeX compounds. To study the correlation of the Ce-4f electrons, we also study the number of occupied electrons of Ce-4f (n_f), the renormalization factor Z, and the Ce-4f_5/2 peak height of CeX at the Fermi level. All these results suggest that CeN is in a mixed-valence state. Among these compounds, CeP exhibits a stronger correlation of Ce-4f electrons than others. In contrast, Ce-4f electrons in CeAs, CeSb, and CeBi are almost localized. These results imply that a 4f-electron itinerant-localized crossover can occur when changing the X atom from N to Bi. Finally, to understand the magnetic properties of CeX, we list six different magnetic structures: A1-AFM, G1-AFM, C1-AFM, A2-AFM, G2-AFM, and FM orders based on the DFT + U method. Our results show that CeP and CeAs have the A1-AFM order, while CeSb and CeBi have the A2-AFM order. These results are in good accordance with the experimental data.