Theoretical Studies on ZnO-Based Magnetic Semiconductors

Sato and Katayama-Yoshida [68] performed first principles ab initio calculations of the electronic structures of TM-doped ZnO and proposed the double exchange mechanism for the carrier-induced ferromagnetism. The first principles calculations predict that transition metals V, Ct Fe, Co, and Ni-doped ZnO [87] showed ferromagnetism with concentration from 5 to 25%, whereas the Mn-doped ZnO shows spin-glass state at ground state because of the exact half-filled d state of Mn ions [68]. For comparison, Cr +, Fe +, Co +, and Ni have d, d, d, d, and 

The local spin density approximation and coherent potential approximation used in the first principles calculation may not be adequate to handle the strong correlation and lattice relaxations. This is particularly so for thin films prepared by different deposition techniques under nonequilibrium conditions. In (Zn,Mn)0, the 3d electron onsite Goulomb interaction Uis estimated to be 5.2 eV, which is comparable 

Venkatesan et al. [107] used a spin-split donor impurity-band model to explain the observed systematic variation of magnetic moments across the TM-doped ZnO 

TM = Mn, and (c) TM = Co. The Fermi level lies in a spin-split donor impurity band. (After Ref [107. ) 

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