First-principles study and electronic structures of Mn-doped ultrathin ZnO nanofilms

doi:10.1088/1674-1056/21/10/106601

摘要/Abstract

摘要： The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO nanofilms. The band structure calculation shows that the band gaps of ZnO films with 2, 4, and 6 layers are larger than the band gap of the bulk with wurtzite structure and decrease with the increase of film thickness. However, the four-layer ZnO nanofilms exhibit ferromagnetic phases for Mn concentrations less than 24% and 12% for Mn-doping performed in the whole layers and two layers of the film respectively, while they exhibit spin glass phases for higher Mn concentrations. It is also found, on the one hand, that the spin glass phase turns into the ferromagnetic one, with the substitution of nitrogen atoms for oxygen atoms, for nitrogen concentrations higher than 16% and 5% for Mn-doping performed in the whole layers and two layers of the film respectively. On the other hand, the spin-glass state is more stable for ZnO bulk containing 5% of Mn impurities, while the ferromagnetic phase is stable by introducing the p-type carriers into the bulk system. Moreover, it is shown that using the effective field theory for ferromagnetic system, the Curie temperature is close to the room temperature for the undamped Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction.

关键词: ultra thin film, ZnO, ab initio, electronic structure, magnetic properties, effective field theory

Abstract: The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO nanofilms. The band structure calculation shows that the band gaps of ZnO films with 2, 4, and 6 layers are larger than the band gap of the bulk with wurtzite structure and decrease with the increase of film thickness. However, the four-layer ZnO nanofilms exhibit ferromagnetic phases for Mn concentrations less than 24% and 12% for Mn-doping performed in the whole layers and two layers of the film respectively, while they exhibit spin glass phases for higher Mn concentrations. It is also found, on the one hand, that the spin glass phase turns into the ferromagnetic one, with the substitution of nitrogen atoms for oxygen atoms, for nitrogen concentrations higher than 16% and 5% for Mn-doping performed in the whole layers and two layers of the film respectively. On the other hand, the spin-glass state is more stable for ZnO bulk containing 5% of Mn impurities, while the ferromagnetic phase is stable by introducing the p-type carriers into the bulk system. Moreover, it is shown that using the effective field theory for ferromagnetic system, the Curie temperature is close to the room temperature for the undamped Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction.

Key words: ultra thin film, ZnO, ab initio, electronic structure, magnetic properties, effective field theory

中图分类号: (Thermal diffusivity)

66.30.Xj

72.20.Dp (General theory, scattering mechanisms) 72.20.My (Galvanomagnetic and other magnetotransport effects) 72.25.Dc (Spin polarized transport in semiconductors)

E. Salmani, A. Benyoussef, H. Ez-Zahraouy, E. H. Saidi, O. Mounkachi. First-principles study and electronic structures of Mn-doped ultrathin ZnO nanofilms[J]. 中国物理B, 2012, 21(10): 106601-106601.

E. Salmani, A. Benyoussef, H. Ez-Zahraouy, E. H. Saidi, O. Mounkachi. First-principles study and electronic structures of Mn-doped ultrathin ZnO nanofilms[J]. Chin. Phys. B, 2012, 21(10): 106601-106601.

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