L’utilisation des calculs de premier principe pour étudier les propriétés structurales, électroniques et magnétiques des matériaux lanthane monopnictides.

Abstract

The objective of this study is to theoretically analyze the structural, electronic, magnetic properties and pressure effect of lanthanum monopnictide compounds LaX (X=N, P, As, Sb and Bi) using ab-initio methods. We have used the method (FP-LAPW), based on density functional theory (DFT). To determine the structural and magnetic properties, we have applied the generalized gradient approximation (GGA) for the exchange and correlation potential (XC) term. The results obtained are in agreement with the available experimental and theoretical data. Additionally, we have used the GGA and mBJ-GGA approximation to evaluate the electronic properties. According to the results of this study, the most stable phase is NaCl for all LaX compounds (X=N, P, As, Sb and Bi), with a phase transition from NaCl to CsCl at different pressures. Through the analysis of electronic band structures, we discovered that LaX compounds (X=P, As, Sb and Bi) found semimetals by the GGA approximation and semiconductors with an indirect gap by mBJ-GGA approximation. However, for LaN was found to be a semiconductor with a direct gap using both approximations GGA and mBJ GGA. The magnetic moment was found 0 µB for the LaX components (X=N, P, As, Sb and Bi) and it was concluded that the X atom has no effect on the small magnetic moment.