ELECTRONIC, MAGNETO-OPTICAL AND THE MAGNETIC PROPERTIES OF THE COMPOUNDS BASED ON THE TRANSITION METALS AND THE ELEMENTS OF THE GROUPS III, IV AND VI.

Abstract

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).