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[en] In this paper, we used the ab-initio calculations, based on the Korringa-Kohn-Rostoker (KKR) method combined with the coherent potential approximation (CPA), to simulate the magnetic properties of ZnO, doped and co-doped with manganese and carbon, respectively. For this purpose, we have used two different approximations: the Local Density Approximation (LDA) and the Local Density Approximation-Self-Interaction Correction (LDA-SIC). Numerical results are presented for the compound Zn1 − 0.06Mn0.06O1−xCx when doping and co-doping is performed with Mn and C as doping elements. Total and partial DOSs are given for different concentrations using the two approximations, LDA and LDA-SIC. It is found that for 6% with doping by Mn the system becomes magnetic. The co-doping with carbon changes the behavior of the system : it becomes also magnetic for 4, 6 and 10% concentrations within both, LDA and LDA-SIC approximations. Furthermore, we have discussed the type of mechanism of exchange interaction and found that the double exchange is responsible for the appearing magnetism in the system, within the LDA and p-d interaction for LDA-SIC approximation. For 10% of carbon, we have found that the critical temperature approaches 280 K in the LDA approximation solely; and is about 305 K in the LDA-SIC approximation.
[en] SnO2:TM (V, Cr, Mn and Fe) based dilute magnetic semiconductors are investigated within self-interaction-corrected local density approximation (LSDA-SIC) from first-principles calculation. LSDA-SIC results are compared with the calculated ones within standard LSDA, the stable magnetic state of the system is evaluated by comparing the total energies of ferromagnetic state and spin-glass state. The Ferromagnetic and half metallic behaviors was observed and conformed with the local-moment-disordered state energy for LSDA and LSDA-SIC approximation in [Sn 0.95 TM 0.05 (V, Cr, Mn and Fe)]O2. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in ferromagnetic states with Curie temperatures within the ambient conditions.