Résumé:
We have studied the different properties of two kinds of materials; the first one is
composed of two transition metals and one non-metallic sp element and the second contains
one transition metal and two non-metallic elements. In this thesis we focused on the
electronic, optical, magnetic and magneto-optical properties of the Pd based compounds
PdMnSb, Pd2MnSb, PdX2 and PdPX where (X=S and Se). We are also investigate the
structural, electronic and magneto-optical properties of the IrMnZ, with (Z=Al, Sn and Sb).
The calculations are based on the total-energy calculations within the full-potential
augmented plane-wave plus local orbitals (FP-LAPW + LO) method. We have used both the
local density approximation (LDA) and generalized gradient approximation (GGA) for the
exchange and correlation potential with and without including the spin-orbit effect. In order to
investigate the importance of correlation, we have used the (LSDA+U) and (GGA+U). The
structural properties are determined through the total energy minimization and interatomic
forces calculations.
The results exhibit that IrMnZ are ferromagnetic and they are mechanically stable at zero
pressure. The local spin density approximation (LSDA) predicts that the IrMnSb is a half
metallic and the IrMnAl compound has negligible magnetic moment. Furthermore, the
LSDA+U and the GGA+U predict a large magnetic moment. Furthermore, the GGA gives
good values compared with the experimental ones. Our results show that the highest Kerr
rotation arises in the IrMnSb compound, while weak values are found in IrMnAl with all the
approximations used.
We have also investigated the electronic and magneto-optical properties of the Heusler
compounds PdMnSb and Pd2MnSb. Our LSDA calculations reveal a gap at EF, predicting a
half metallic nature in PdMnSb, but the LSDA+U and the GGA+U destroy this gap. We show
also that the LSDA+U can produce accurately the optical properties, while the magnetooptical
properties are well reproduced with the LSDA. Furthermore, we found that the
magnetic and magneto-optical properties are sensitive to the change of the U parameter.
The structural and electronic properties of PdX2 (X=P, S and Se) are investigated. Our results
show that the studied compounds exhibit a metallic character with LDA. Furthermore, the
LDA+U predicts that PdS2 compound is a semiconductor with a narrow gap. The calculated
anisotropic frequency dependent dielectric functions, reflectivity, refractive index and
absorption spectra are obtained and discussed for PdPX where(X=S and Se).
