Browsing by Author "T. Ghellab"

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    Effect of octahedral cation on electronic, magnetic and optic properties of CoX2O4 (X = Cr, Mn and Fe) spinel compound
    (UNIVERSITE MSILA, 2022) N. Hetache; Z. Charifi; T. Ghellab; H. Baaziz; F. Soyalp
    The GGA+U approximation is used to compute the magnetic, structural, and optical and electronic properties of CoX2O4 (X = Cr, Mn and Fe) spineles. For these spineles, X has an effect on their behavior.The problem of the relationship between the relative forces of the exchange effect and the crystal field effect was investigated via a comprehensive examination of the densities of electronic states in order to get a better understanding of the electronic aspect of these compounds.It is only by the introduction of electron-electron interactions between magnetic cations that it is feasible to get the correct ground state. Changing the X cations causes a complete shift in the crystalline structure, which goes from cubic normal spinel for CoFe2O4 to tetragonal normal spinel for CoMn2O4 to inverse spinel for CoCr2O4.While our spineles exhibit considerable differences in their electronic behavior, an increase in the band gap from Fe to Mn and Cr compounds has been seen in our spineles. The occupancy of sub-lattices in the inverse phase of CoFe2O4 and the presence of severe structural distortion in the CoMn2O4 compound have a major impact on magnetic exchange interactions.In order to predict the trends of magnetic exchange couplings, it is necessary to analyze structural characteristics as well as electronic structures. Because the iron states in CoFe2O4 are tightly confined, this spinel differs significantly from the X cation states in the other two spinels, as shown by our observations. The change in X cations thus enables us to validate the trend in the characteristics of CoX2O4that has been observed.Prediction of optical characteristics is achievable, and we were able to compute a variety of optical parameters using this method. We've found that the value of  1 0 lowers as the band gap increases.