Electronic structure and magnetic properties of Cr monodoped and (Cr, Al) codoped ZnO

Using first-principles calculations based on density functional theory, we investigated systematically the electronic structures and magnetic properties of Cr monodoped and (Cr, Al) codoped in ZnO. The results indicate that Cr monodoped in ZnO favors a spin-polarized state with a total magnetic moment of 7.50μB per supercell and the magnetic moment mainly comes from the unpaired 3d electrons of Cr atoms. In addition, it was found that the ferromagnetic exchange interaction between Cr atoms is short-ranged in Cr monodoped ZnO. Interestingly, the ferromagnetic stability can be enhanced significantly by codoping AlZn. We think that the enhancement of ferromagnetic stability should be attributed to the additional electrons introduced by AlZn codoping.