The geometric structures, electronic and magnetic properties of Mn-doped ZnO nanowires were investigated using density functional theory. The results indicated that all the calculated energy differences were negative, and the energy of the ground state was 0.229 eV lower than ferromagnetic coupling, which show higher stability in antiferromagnetic coupling. The calculated results indicated that obvious spin splitting phenomenon occurred near the Femi level. The Zn atoms on the inner layer of ZnO nanowires are easily substituted by Mn atoms along the [0001] direction. It was also shown that the Mn2+-O2--Mn2+ magnetic coupling formed by intermediate O atom was proved to be caused by orbital hybridization between Mn 3d and O 2p states. The magnetic moments were mainly attributed to the unpaired Mn 3d orbitals, but not relevant with doping position of Mn atoms. Moreover, the optical properties of Mn-doped ZnO nanowires exhibited a novel blue-shifted optical absorption and enhanced ultraviolet-light emission. The above results show that the Mn-doped ZnO nanowires are a new type of magneto-optical materials with great promise.
Keywords: ZnO; density functional theory; dilute magnetic semiconductors; magnetic property; nanowire.