First principles study of the electronic structure of Al/Ti:ZnO crystal

We present results of ab initio calculations in the Local (Spin) Density Approximation, L(S)DA, of the electronic structure of Al and Ti doped ZnO crystal. Whereas both dopants modify the density of states at the Fermi energy, the structure and population of the impurity band is different in the two cases. Our results predict a non magnetic ground state for Al doped ZnO crystal, with the concentration x(Al)= 2-20 at.%. In the case of Ti doping the calculations predict a magnetic ground state and we obtain a magnetic moment localized on Ti ion of 1.14, 1.20, 1.28 and 1.54 mu_B/Ti ion for x(Ti) = 2, 5, 10 and 20%, respectively. We discuss the results in terms of the carriers role in the interplay between conductivity and magnetism in these materials.